Hi John!
Currently there are two 1/72nd scale Type VII models available from Revell.
One depicts an early VIIC with the small conning tower, the other is meant to be a VII/C41 with the full two level wintergarten. Both kits are approx 4 feet or so long and retail (in the UK) at £50.
Early one:
http://www.hannants.co.uk/search/?FULL=RV5015
Late one:
http://www.hannants.co.uk/search/?FULL=RV5045
If your budget and space requirements don't stretch that far, Revell released a Type VIID minelayer in 1/144 scale (approx half the size of the two big ones).
Type VIID:
http://www.hannants.co.uk/search/?FULL=RV5009
Revell also did two 1/125 kits of U-99 and U-47, the latter being a cutaway. To be honest, avoid those two like the plague. They're not very good!
U-99:
http://www.hannants.co.uk/search/?FULL=RV5054
U-47:
http://www.hannants.co.uk/search/?FULL=RV5060
Hope that helps,
Mike.