Artillery, commandos, and double LMG tommies kicked my but every time I tried to Pak wall Brits ;_;
EDIT: Honestly I'm just giving my impressions of how the Alpha was, stuff has probably changed and brits have new weakness's but the one that I always exploited was just using buttloads of cheap replaceable tanks/infantry. Puma's, StuG's, Ostruppen, ect.
The issue with the Comet is it had no weakness's. Excellent scatter, good AoE, good armor, excellent speed, only slightly less penetration than a Panther. While coming as part of Hammer which once you unlocked you didn't need anymore teching for. The Panther is at least weak to AT guns and infantry, the Comet really didn't have anything you could exploit.
As I said before, the way to fight UKF was to close the game early on with mediums, once the game escalated to the late game you simply couldn't fight off UKF due to their insane commander abilities and plentiful anti-heavy AT.
Vet 5 should be removed and just more stuff packed into vet 1-3. This is how the brits will work, so I don't see why USF and OKW couldn't get this "feature".