Just tried accessing the appointment link here at work, and for some reason it all went through fine! I don't know what the problem was on my computer at home, but thanks again for suggesting I try another browser.
Discovered that someone must have read my email, because when I attempted to book the appointment just now, I got a response saying I ALREADY have one scheduled! HOORAY! The only thing is, I don't know what time, so will still phone them later on if I haven't received an email from them by then.
Do I sound a little anxious? I can't wait for this to all be done!