There are tons of options ranging from £6 ebay/china specials right up to £100+. Sourcing them is a different matter.
What are you going for looks wise...the general consensus is that a muzzle brake/comp/flash hider, does nothing for the muzzle rise on a 22lr.
Ignoring that, i put a Tandemkross Game Changer Compensator on mine...was a bit of a schlepp getting it on (specifically made for 22 pistols) but after i did it looks the business and in my opinion the rifle runs a little flatter and the sound signature has definitely changed, for the better.
You can get all kinds of fake cans, brakes and shrouds, Tacticool 22 even does a 22lr specific brake. Sourcing them UK side, Brownells obviously and the variety of UK black rifle dealers sometimes have a limited selection.