One issue I was not prepared for is supply. I had expected the major ports of Brighton and Dover to provide major supply, but I didn't read the rules carefully enough. There is parameter data:
which indicates that those ports are 'suppressed' for 28 days. During that time, they will only offer minor supply, with a supply range of 12 movement points, if I read it right.
Currently I'm only getting amphibious supply, and I don't yet understand why I'm not getting minor supply. Hmmh.
[later]
Turns out Brighton and Dover are minor ports (lower case lettering), and they are currently colored orange (ie suppressed), meaning they offer no supply. So indeed, all my army is getting is amphibious supply. That severely constricts my chances! It is imperative now that I take a major port: London.