Paul asks: Where do you get the resin tanks from that you use on the warflats ?
The simple answer is that they can be supplied with the kit when you buy it from the Double O Gauge Association.
However, this isn't very helpful. As I recall, the supplier is Gramodels who produce a range of military hardware in several scales. I recently used a Ferret armoured car on my pizza layout for BRM.
When loading a Warflat, remember that not all armour will fit within the loading gauge. Early tanks and armoured cars will be fine but you won't squeeze a Challenger through a tunnel!