Arthur is quite correct, for fiancee visa you need to be free to marry and will need to submit evidence of that.
But I think it's a good idea that you will start some preparations by researching here in the forum on the documents and the evidence you will eventually need once you have the annulment papers finalised.
Please take a look here for Fiance(e) Visa Guide
and look here at UKBA website for Fiance(e)
Just follow the links
Hope this helps. I'm sure you'll find plenty to keep you busy.
Did you pass the English Language test yet?
You need to get that step done asap
Don't feel shy to ask any questions that you need to find clarification for