short haul business class on BA is not all that great tbh. If you were flying medium haul i.e eastcoast us, middle east destinations its better as you get the proper business class seats that stretch out into a decent sized beds. Short haul business class just means slightly less rubber vulcanised tasting in flight meal and slightly more room in the seat to fit your ass cheeks into.
T5 lounges are ok, but you can only use 1 of them unless you are a gold BA card holder. The gold card one is a lot better. But still worth going in there for free liquor, grub, paper, shower, dump on a clean comfortable khasi, wipe ass with softer paper aspects