When playing as UKF, In my opinion you need to get 5 men upgrade as soon as possible while also getting an AEC out to counter light armor play...
Now you maybe saying if I get 5 men upgrade, i'll be even more vulnerable to a P2 or a 222 and the answer is NO. If you get 3 REs with double PIATs (even though PIATs are as we all know are shit) they are gonna hit something eventually.
Oh and if you need a build order, Here it is :
Starting IS
IS
MG
T1
RE
5 Man Squad
AEC(if you see/suspect light vehicles)
RE(if not going AEC)
RE
Sniper(if the enemy is OKW and the map is open and long range depended)
Sniper
T3
Cromwell
Cromwell
I'd replace the second RE with a sniper then a 6pdr.
Also never get 5 man squads till after I get Cromwell.
My build order:
-Starting IS
-Vickers
-IS
-tech
-sniper/RE
- the other of two mentioned above
-6pdr
- 2nd sniper or Vickers
-tech t3
-Cromwell
-bolster squads
- Cromwell /Hammer
Also note that having tactical support regiment allows you to get a free Vickers and ATG for 150 munis