No worries Marc, I'm glad you got it working.
I think next time you want to download new dives, I've found I have to put the phone and the dive computer next to each other, and go to the pairing screen, which will say something along the lines of "no need to re-pair..." And then subsurface is able to connect to it.
It doesn't seem to work if you don't do that extra step of opening the Bluetooth menu, which is odd, but it could well just be my phone being a bit rubbish.
I'd be interested to hear how it behaves for you?
Cheers
Colin