Capital Ships or Carriers in CAREER?

Greetings folks, although I have long been an owner of SH3, I have never go online with questions. So here is my first:

Is it possible to encounter battlegroups in the career mode? It is December 1940, and I have been sinking ships like crazy (my realism is pretty low, no I'm not that good). But although I have been on 13 missions so far, and I patrol quite close to Scapa, Flow, Loch Ewe, and even Dover, I have yet to see anything beyond a destroyer warship besides one light cruiser.

Thanks to any and all help! As my captain is the leading sub ace by some multiplicative factor (4x?), I would really start hunting the big guys if I can, and I do not care at all if that kills me

Thanks.
Tortuga Power