Great Britain led Allied efforts in almost every global military theatre of the WWII. Despite the initial failed campaign along Europe, Great Britain slowed, or even stop the Axis advances in many fronts, meanwhile a great military industry was developed.
The British field some of the best infantry in the game, which greatly helps them gain land in the beginning. The HQ squad is rather small, but it is the only HQ squad to provide with light machine guns and is the fastest way to get infantry ifre support this early on.
Lots of tools the british have empasize this, like a rather cheap armored infantry transport and glider infantry. In most situations, when you see your enemy has a similar amout of infantry, expect a rather swift victory.
The british have some good anti-tank aircraft as well, making for very risky combo's, allowing you to play quickly, not giving others time to understand what you are doing and where you're gonna hit next.
British weakness lies in armor. Not to say that britsh armor is bad, but it's either overpriced, or pretty easy to destroy. In the end, you're more likely to use tank destroyers, as the heavier versions become very efficient and easy to use overall.
One other rather annoying aspect of the GBR faction is the artillery. Despite having the longest ranged guns in the game, they deal several times less damage, making them at most infantry support weapons. Using them to destroy buildings will take longer than usual if you don't have any sight of the location.