Mick: Sounds like you're going to have some fun there! (My degree's in mathematics so I quite enjoy the challenge of doing those sort of things but I can understand that not everyone else loves the task!).
Over the years, I've seen various public domain programs for fixture generation but, even if I could track them down, I suspect that they might do no more than the website.
There is a program designed for bowls club secretaries which might suit your needs (after all, the structure of a fixture list is the same, whatever the sport). You can download it from here:
http://www.download.com/Bowls-Fixtures-Calendar/3000-213 6_4-10432897.html?tag=lst-0-2
The program only functions for 30 days - after that it'll cost you $35 - but that should be long enough for you to see if it's any use.
Chris