If you’re sure you’re going to stick to 200 yds, then .223/.222 is perfect, but if you might get a taste for longer range in the future, it may be a good idea to look at a larger calibre, a 6mm or 6.5mm, still not .308.
As for a scope, if you can stretch to £500, you might pick up a Sightron S3. Always worth spending as much as you can afford on the scope.
good luck