I'm also in Norfolk and would second a trip to WEX. Well worth it as they have a big range of stuff to actually pick up and test.
The size in your hand and how it handles, not to mention how good the viewfinder is will matter a great deal.
If you have previously used manual film cameras, you might like to try the Fuji X series of cameras, because they rely less on buttons and menus and have nice tactile controls.
My 70yr old Dad just got an Olympus OM-D E-M10 mirrorless which he finds really good as someone who used to shoot on Olympus OM2 and OM4 film SLRs.
The thing with shooting wildlife is that you need a decent telephoto lens, which at the lower end of the budget usually means only an aperture of f5.6 or 6.3, which means you need to get your ISO up to get a decent shutter speed.
But unlike in the film days, you can shoot at ISO 1600 and beyond without worrying.
Also, if you're in Norfolk, you could consider joining the Norwich and District Photographic Society, which is full of like-minded people with lots of experience. Usually it meets on Tuesday evenings in Norwich, but in the current climate, they are meeting via Skype with a full programme of talks and things.
https://www.ndps.info/