Thanks everyone so much for taking the time to reply - it's great to get your advice and has helped me feel much less alone in dealing with this.
I just wanted to give you a quick update: I saw the urologist this afternoon, who gave me a DRE and found nothing of note. He's given me a course of Ciproxin (500mg tablets twice daily for a week), and Topster (suppositories - 1 each evening for a week) to eliminate/rule out any infection, Fifteen days after that I'm supposed to repeat the PSA (but for free, total and free/total) and get an ultrasound of the urinary system and a flow test done.
From what I've been able to glean online, I gather that this is a fairly standard approach (and to be honest I'm just happy to have made a start with things), but I couldn't help noticing he decided not to go with the MRI that Chris expected, at least for the time being. As I'm still very much in panic mode, with every ache and pain scaring the hell out of me, I'm wondering whether that's something I should maybe be asking my GP for in the meantime. Just to be clear, I live in Italy, so I'm guessing things may possibly work differently to the UK. In particular, although there are a lot of great doctors here, I get the impression that the system isn't quite as intergrated as it is in Britain, meaning patients might sometimes need to take the initiative a bit.
That's all for now - thanks again to everyone for all your advice and kind words.!
Cheers
Dan