We're planning to get married in the UK in August. She's also starting university in the UK in September.
It would seem that the logical progression is marriage then school. So if that's the case, why not a fiancée visa as marriage comes first?
I've phoned the immigration office a number of times about what kind of visa to get and I always get different answers.
Don't feel bad, I've had that happen too.
Sometimes they say she can get a student visa and after we're married she can get 'further leave to remain'.
Now this seems really odd because they've just changed the laws so that you can not change your status once you are in the United Kingdom; you must do it from your home country. There have been a few people on some forums that have had to go back to the US to change their status. However, from what I can remember, none were in your situation.
But other times they tell me she needs to get a fiancee visa.
I would think that the fiancée visa would be best, merely because it shows your true circumstances and the fact that your future wife intends to reside in the UK longer than her period of study.
It couldn't hurt, however, to consult an immigration lawyer, especially if you are getting the conflicting information from the Home Office. Also, it may be worth writing the HO and getting their recommendations in writing.
I would also check with her school and see if her fees or such would change if she were to come on a fiancée visa, just so you have no nasty surprises.