Missing Missions in Britain

Hi --

I'm new to the game and just finished playing a couple missions in Northern Britain. As near as I can tell, they're the only fixed missions available in Britain for me... I'm playing the Allied mission and, when I first landed, saw only the "Agent's Cache" mission (where I caught Obersomething Brunst or whatever his name is). The info I found there opened up the Old Mansion misssion (start off surrounded by bad guys, capture Major Newhouse). So far, so good... but then I checked the walkthrough and it looks like there are supposedly another two or three missions in Northern Britain. But my plane's already flashing and there's nothing to indicate any more set missions on the regional map, only random encounters.

Is this common (because I'm playing easy level)? Or did I miss a piece of info somewhere that would have unlocked the other missions (I fulfilled all my objectives and thought I searched pretty thoroughly)? Or did I do something else wrong?

Just to check, I left the regional map and the next region that's open is Hanover. What about Southern Britain (according to the walkthrough)? I have the Thor's Hammer info, etc., which I guess is what opened up Hanover.

There are still plenty of random encounters to train my guys up on before I proceed, and one of these days (hopefully tonight, now that I've got a few levels), I'll kill those darn ninjas... tried again on my third battle, and got slaughtered -- just can't seem to find them until they're already throwing grenades and slaughtering us with stars from close up. But now my spot skill is better, so I'm crossing my fingers.

Anyway, any advance about the missing missions -- are they really missing? Why? -- would be greatly appreciated. Thanks!

SF