hi Sal,
here's some info..
http://www.hmcourts-service.gov.uk/infoabout/d ivorce/index.htm
the only grounds for divorce with less than 2 years separation are adultery, desertion and unreasonable behaviour. you have to have been separated for at least 6 months.. it's not a time limit, and you will have to give your reasons, regardless.
otherwise it's after 2 years separation with both parties agreeing, or 5 years if 1 party is not agreeing. you will still have to state your reasons on the court papers.
I'm off to work now but give me a shout if you need more info. I did my divorce myself after 2 years separation, and it was quite straight forward and much cheaper than using a solicitor x