Want an electronic view finder, or happy with just a screen ?
Probably at that price range a second hand micro 4/3 camera from Panasonic or Olympus with a kit lens.
Maybe an older Sony such as a NEX-5N, although Sony glass going forwards is a tad more expensive
Any recommendation for a mirrorless camera for around £250 - happy to buy secondhand, so what's the best I'm likely to get for my money?