Hi Simon, welcome here.
Seriously, there is a host of civilian vehicles which were acquired by the armed forces. They were mostly militarised to some extent, but often no more than olive drab paint, some rifle and first aid kit. Volkswagens are still supplied in large numbers to the military, in fact, ever since the VW factory supplied the majority of it´s early post war production of Beetles to the occupation forces.
If I were you - interest in trucks and living in the UK - I would go for one of those 1950s British trucks. I see them popping up here in various conditions, but those ex-war reserve stock trucks look like very good value for money.
Regards,
Hanno