i play few game against brits and bofor is super effective against imf and light vehicles and damage stug and ostwind.
you can try with Pz4 or mortar
P4 takes too much damage, risky or impossible unsupported, only way is keep it braced with in direct fire and use something with high vision to wipe it. I feel against brits both factions have to just bleed them so they cant get tanks and then overwhelm with spearheads of armor once the balance tips.
I guess spotting scopes as ost will help a lot. As OKW I just keep a leig hammering them till my jagdpanzer can come. P4 against brits is risky as they pack a punch and thier at has soo much range.