Horses for courses.
In days of yore cameras came with one, fixed focal length lens, usually around 35mm or 50mm, depending on film format. And folk got great photo's with them.
Start going 'zoom' to pack in a greater range of focal lengths, you have to pack in exponentially more compromises. They will tend to be more expensive, for starters; they will almost certainly not be as 'rigid' and mechanically durable, or have the same degree of optical 'excellence', usually exemplified by slower maximum apertures, and often zoom dependent apertures getting relatively slow at the longer telephoto end of the range....
For landscape? Wide is not always better; more land does not more landscape make. I have often wandered about with a big bag of primes on my hip, and my cast iron Sigma MK1 film camera, got home, and wondered why I strained my shoulder, when all I used all day was a 29mm! I'd have done just as well, leaving all the heavy-metal behind and taking 'just' my Konica C35, with it's fixed 35mm mild wide lens! I have though, found a mild telephoto, useful enough to isolate smaller patches of scene, but even there, never really much over 70mm, An 18-55, on crop-sensor camera, probably covers pretty much all bases.
For portrait work? Space, setting and lighting are the key ingredients. a 90 or 135mm mild tele used to be the common portrait lens for 35mm, and was supposed to give a more 'flattering' perspective, mostly from begging a grater camera to subject distance. An 18-55, at the long ed, just about gets in that effective range, again making the standard 'kit' lens a pretty good starting point.
For close-up work, snapping small artifacts; you are into a region of specialization, where a 30cm closes focus distance is likely rather restrictive, especially for frame filling. The closest focus distance of most zoom lenses will not be a lot closer, and more zoom may give you more scope for frame filling, it's a lot of compromise for little practical gain. If I were to dabble in this specialty more regularly, then I would probably be looking at a fixed prime lens, as zoom isn't all that pertinent, and for close focus extension tubes or bellows. Demands of critical focus at such short camera-subject distances would probably disecline me even from the expense of an Auto-Focus lens, especially as that feature would likely be redundant on bellows anyway.... and I would probably be looking for an old film era manual focus prime..
I confess I am not a fan of super-zooms one little bit. Idea of buying an all singing all dancing DSLR, whose main asset it the rapid interchangeability of lenses, to slap a single, highly comprised, do-it-all lens on the front, seems rather anathamic. May as well save pennies and buy a super-zoom bridge camera....however
End of the day its your call, what compromises you are prepared to make. And with £300 odd quid to play with, personally, I would, or what you suggest, be thinking along the lines of a 'better' more moderate 'standard' zoom; top of the chart for my own thinking there being the Sigma 17-50, for landscapes ad general walk-about, and enough 'scope' for portraits, and useful boost in both potential IQ as well as max aperture.
Alternately, if more concerned with close up if what you already got good enough for walk-around, landscape and portraits, and I don't see extra zoom being big advantage; then I would forgo that, at least fr now, to put investment into more dedicated close up kit. And with good manual focus 50mm primes available for under £50, and extension tubes or bellows not adding much to that; it would leave a lot in the pot to put towards such other necessities as a decent tri-pod, ring-flash, or other artificial lighting, props or sets for the genre.. and likely STILL leave a hefty start towards a better general purpose lens for landscape/portraits, or if you feel you really need it 'more zoom' from something with more reach... in fact; even there, if you made the compromise to forgo Auto-Focus, you could probably buy something 'prime' in the 135-300mm range, maybe even a couple! All within budget, and probably with better potential Q for the cost, and amount of actual 'use' they would likely get.
Plenty of great legacy lenses about, and on a Nikon body, plenty of them don't even need an adapter. But, accept that compromise, and splurge maybe £20 on an infinity corrected adapter mount, and you could fit some cracking legacy lenses that cost absolute peanuts relatively.
If it were me, I already have an M42 adapter, and occasionally mount the screw-fit rimes from my old Sigma MK1. I have a fantastic Ziess 50, which would do very very nicly on bellows for close up, and is worth perhaps £20 on e-bay! I have a Prinz 300, which as a 'cheap' budget brand of its own era s much maligned, still manages to out-perform kit lenses of that focal length on widgetal, thanks to the crop factor bonus, only taking image from the sweet-center of the mage circle, as well as being a rigid, uncompromising and 'simple' construction... its more faff than an automatic AF lens, but begs more thought to use, and that too can aid results demanding greater forethought and diligence... but those are compromises I choose to make...
Which s the point. A long range super-zoom, is dictating the compromises you MAY make, before you even begin, just for the convenience of a one-size-fits all lens, that ever has to be taken off, defeating buying an interchangeable lens SLR to start with!
Have spent about five years and best part of a couple of grand to get the same effective range of focal length for digital as I enjoyed for film cameras.... most of it at the wide-side, I will say. the kit 18-55 remains however my most used lens, pretty much as the 28-80 did on my 35mm film camera. Not having more zoom is no great handicap; swapping a lens is no great burden; lugging one or two about might be, but as the 29mm on the Sigma suggests, no huge impediment not having it with me at all, and even just the moderate zoom range of an 18-55 is probably more than enough a lot of the time.
End of the day its your money.... but, I would thnk long ad hard about your actual needs, aspirations and objectives here, and just how much you would get from a longer range super-zoom, for the money, and how many extra compromises you would be buying yourself for that small convenience. There are many ways to skin a cat, as they say, and splitting the variables, tailoring the compromise to the job on hand, exploiting the interchangeable lens mount, and looking at other possible solutions, like legacy lenses, bellows or extension tubes, I really do think you could get so much 'more' of what is actually likely to aid you dong what you suggest, for your money.
It's still quite a lump to carry around if you're only going to use the 100-300mm range occasionally.
