Also, if you head up to the North-Eastern-most point in GB, there's 2 harbors you can find some action at. Just don't burn through all your petrol in transit and your patrol grid.
Type IID (I think - either way, the other type II) have a VASTLY extended range over the IIA. This will let you get into the meat of the Channel, if not the Western Approaches. Also, you can always dock at Wilhelmshaven (if that's the right name) for a refit and refuel.
I'm currently stuck with a Type VIIB, wanting an upgrade badly.
Not that I recommend this, but you can alter values for upgrades and costs in the basic.cfg file. That includes the years that subs are available. So you COULD start out with a Type XXI boat.... BUT that would only be fun for so long.
I'm also very new to the game, but I honestly ask that you give it another chance. I think it's worth it.
Cheers!