Take it slow and easy (stay as relaxed as poss). Don't expect too much, and MAKE SURE YOU GLOVE UP!

I am sure you have already, but make sure you are both 100% commited to the idea by discussing it. It may also be a good idea for your girlfriend to visit a gp for advice and perhaps additional contraception, doubling up is always a good idea.

If you do go ahead, best of luck, enjoy