Hello,
I wanted to say thank you to everyone - last night, I got it to work using all your advice. Firstly, it seems that reinstalling everything after the ASCOM driver allowed PHD2 to talk to the mount properly this time. And secondly, I was not calibrating away from Polaris - as soon as I followed your advice and ran the calibration nearer the south horizon, BINGO!! First run was a bit off (RMS Total of over 2). Second run was much better (RMS of around 0.5)
Still a huge amount to learn, but now I can get images and have a baseline, I can build on this.
Thank you to everyone for the advice ,you have no idea how much it helped!!!