Thanks guys, I think I've got there. I have a Google account already, mail and checkout and suchlike. I installed Outlook (it was on my Office DVD, no problem), which the Nokia PC Software will let you sync with your phone. Then I exported as .CSV from within Outlook - I tried iCalendar but it wouldn't work. I exported my contacts straight from the Nokia software to .CSV.
Everything's working but I did find a few glitches. My contacts had most of the details in the notes section, so instead of populating the Date of Birth section on the website, it just displayed it in the notes. I put this down to Nokia's software exporting in a slightly different format to what Google expects and I've corrected things by hand. It's also been a good opportunity to clean it out a bit. A few things in the calendar are different, like events not repeating, but I'll sort them out in due course.
Why is the contacts page so hard to find? I had to google for Google Contacts to find it.