just started playing and have a few questions

[Mobhack]

See the Game Guide -> cross attachment screen for assignment of any free platoons to company HQs.

Some folk will religiously attach spare platoons, others don't bother and leave them under A0 - especially say transport platoons which may be better assigned as required by the battle perhaps.

I will usually attach spare combat platoons (rifle, tank) to make up company combat groups, and leave any supporting transport, recce, resupply, AAA, battalion guns/mortars, CS tank sections etc under A0 in "A Company".

As to purchasing the game in the UK - or anywhere else in the world - see the the link right there at the top of the forum entitled "Order WinSPWW2 here". There is the choice of the physical CD, or a digital download. The latter is instantly available, with no wait for delivery.

Cheers
Andy