Getting paint to stick to plastic is always one of my worries. I hadn't heard of Make Paint Stick, so I'll have a look at that, thanks.
After a quick search, the can I found was £92.36 + £2.80 p&p

, but other adhesion promotors (my new words of the day) look more reasonable.
Methinks a trip to B&Q at lunchtime may be in order.
Really enjoying what you're doing with the tank, looking forward to seeing it finished. I'm a fan of classic black and green NATO camouflage myself, but the Stuka scheme looks good.