How the fuck do I play Britain 7.7/8.0

I'm having trouble with british 7.7 because the sabot rounds really seem to suck ass. The only thing at my br that I can reliably pen is the leopard 1, being able to punch though the turret and hull. Of course if i get down tiered I do well, king tigers arnt a problem, and Pershings can be annoying, but if I get 7.7 to 8.7 I'm fucked.

I can kill things like the T-55, T-54, T-10M, IS-3, IS-4M and IS-6 through the turret pretty well, but not before they put a shot into me first, and usually that results in me dying. Things like the T-55AM-1 get APFSDS, and my poor centurion only gets 100mm of pen at 60°, and richochets all the time. The conqueror is better, but it's reload is 10 seconds longer and the hull armor is shit. Not to mention how slow the British vehicles are, going a top of maybe 20mph on a straight line, and about 13 normally.

The lineup I use is the centurion mk3, caernarvon, and conqueror. They always seem to be penned by everything, even in downtiers. Though in downtiers they are very effective, I can pen things like the T-44 and King tiger through the frontal plate, but both those things can still kill me. I've learned that the turret armor on British vehicles is good, but the hull armor is ass, so unless I can go hulldown I'm basically just a tank made from wet sand. That moves at 15mph. With a gun that bounces the side of an IS-6 (well, it doesn't bounce, per say, but it goes in, doesn't spall, and goes through the other side causing no damage).

Is this a skill issue, or is Britain really just bad? I've heard people say that Britain tanks are garbage, and that British mains are the best at the game because they have to be, but is that true?