Budget implies 2nd hand; You aren't likely to get anything that's 'full-frame', as in 24x36mm sensor size, the same as a 'fullframe' 35mm film camera; for that kind of money.
You could find some very useful 2nd hand APS-C 'Crop' sensor DSLR'S in that budget; they use a 16x24mm sensor, about half the size of a 'full-frame', and the same dimensions as an Advance-Photo-System film camera, or a 'half frame' 35mm like an Olympus Pen.
Micro-four-Thirds, from memory is aprox 1/2 the frame area of APSC or 1/4 the area of a 'full-frame'; and as a less 'popular' system, its one you could luck in on and get a pretty creditable 'outfit' 2nd hand for that sort of money.
One thing is for sure, £200 is about £100 shy of entry money for anything over the counter 'new'.
The MFT system, could be a very attractive place to start on a budget; the system, though is limited by that small sensor size; smaller sensors mean greater crop-factor; makes longer lenses effectively longer, but that works both ways, and you will struggle to find short lenses short enough to give the same sort of wide-angles they have on larger sensors. System has its fans, and a lot of them like using older legacy lenses from film cameras on them on adaptor mounts; but the support the system has is limited, and you don't have such easy, cheap and convenient access to such a wide range of lenses or other accessories; whilst the system IS limited by that small-size sensor in some effects and aplications. To my mind, if you know enough to make an MFT system work for you.... you wouldn't be asking the question what to get! It is a system for an already knowledgeable enthusiast who apreciated the few advantages the system might offer and who can live with or work around the systems 'quirks', rather than a new comer who probably wants to explore what they can do with a more sophisticated camera.
As such, I would tend to steer a newbie, towards APS-C sensor entry level DSLR's, and specifically the entry level Nikon or Cannon's... as those are the two dominant systems, with wide range of lenses and accessories available to support them, readily and usually quite cheaply available new or used.
Entry level kits start in either brand between about £300&£400 depending on on the day discounts or offers; and they are VERY well tailored to their intended market, and newby-freindly funtions; Likely that you would only get one lens, probably the very versatile 10-55ish kit lens with the camera body in the cheaper kits; but its enough to take you a long way, and give scope to build up an outfit, 'pay as you go' bit by bit.
2nd hand? you would get more for your money, if you hunt about. I bought two 2nd hand Nikon D3100's last year; one for my daughter for school photo; and I paid I think £120 for the camera body from a dealer, with warranty; I bought her a 35mm 'prime' lens to go with it, off the for-sales on here, for I think £80, to give her a 'solid' starting point to build a kit around, and the versatility she needed to do course-work. Bought a second one for my O/H who was feeling left out, off a Gum-Tree add, with kit 18-55lens, for I think £140.
So if you are happy to take a slightly out-moded entry level camera; you are likely well within budget and could have change to get a bag, spare batteries, maybe a tripod on top.
MFT... you are likely to get a lot more upfront, from some-one selling up; but picking up where they left off; as you progress, you are likely to find that when the outfit you have got runs into the buffers, to go where you want, is either going to be expensive staying in the MFT system, or switch to APS-C or FF is going to be an even bigger and more expensive 'leap' to replicate the MFT outfit in a new system, and then expand on that.
So.. three things:
1/ clarify what you mean by sensor sizes, formats and systems.
2/ contemplate hard, how much you want to get 'in' to photography; what you take photo's of now; what would suit that; and what you might like to try in the wider world of photography, and what may be needed for that.
3/ think hard about the budget; £200 will get you going; but, beyond that, choices you make now, could make it a heck of a lot more expensive later, or let you get better value from more later.
but £200 will get you an older MFT body and a lens, possibly two lenses, or you could get a body and some cheap film era lenses and use them via an adapter.