Kaluen,
Since you are using SH3 why not start in a base with the IXB available in 39?? Many bases have different availablity dates on different models. I always pick 2nd Flotilla, starts in Wilhelmshaven then Lorient, it has a wide variety of boats as well.
GL and Happy Hunting!
PS the SH3 game manual also has a chart in it with boats and dates of availability etc.