Lovely brush work on those mini miniatures. They are very nice. Looking forward to seeing your Brits.
As for your rules. I would highly recommend you look at Iron Cow by Wessex Games. They are aimed at 6mm / 1/300 but will work with 3mm. DS2 is a good solid set of rules, has s nice design system so you can build your vehicles. not played Strike Legion so I can’t comment there.