Brits dont have on map arty except suckmortarplacement whitch is instacountered by mortar halftruck , so i think its fine.
Also oshteer gets faust on every core ifnatry while brits get faust only on sucky specialisty infantry that use prebuffed PTRS , so i think its fine that hteir at gun is cheaper because its their only at option mid game except of armored car that die to doubleshreck , cant fight ifnatry and slows teching.
Just my 2 cents.
All factions have their pros and cons.
Also brits doesnt get pak 43 with their arty or i win prostruppen button (it is i win button agains brits actually)
i'm not positive but i don't think i've ever seen the brit AT nade cause engine damage.