Pete, let us know how you get on in the future, be very interesting. I've mentioned it a few times before, I had the pleasure of a tour of U534 before it was cut up into sections, I was in Birkenhead at the time looking after one of the company vessels that was laid up.
After signing a disclaimer (a form saying we wouldn't sue if we got injured) on board an old lightship, we moved on to U534, just before the tour, the Guide asked if anyone had been on a submarine, I stuck my hand up and said yep, Trafalgar class and Trident class subs.... the guide looked over my shoulder and said "and you Sir whats your experiance,"
"I used to sail on one of these"

The Guy was on his second tour when they surrendered, he was taken POW and was in a POW camp in Wales, after the war he stayed in Wales as he had nothing to go back to in Germanyicon.
never had much time to talk to him as he was with some of his family, just wished I'd had more time and get his details etc.