serious question here, how familiar are you with your own laws? i highly doubt you are even a fraction as knowledgeable on them as i am and i don't even live there. examples of uk legal firearms under a section 1 firearms certificate...

ruger 10-22 semi-automatic rifle chambered in .22lr with 25 round bx-25 magazine...



various saiga-12 12 gauge shotguns with detachabke box magazines, as long as the barrel is 24 inches its perfectly legal...



savage model 111 chambered in .338 lapua which is very similar to the gun used to make the longest confirmed kill in history at over 1.6 miles, which funny enough is held by a brit. there might be some cosmetic restrictions as far as muzzle breaks are concerned, but otherwise this rifle is perfectly legal...



one of the many silly long-barrled pistols which along with black powder and certain historical models, are perfectly legal "handguns" in the uk, although regular modern designs are allowed in both the isle of man as well as northern ireland...