If you plan to live in the UK after you're married this is your order of events:
- Apply for
fiancee visa - After receiving visa, leave for UK. You cannot work or have access to public funds during this time. You have to prove that your girlfriend can support you without government assistance
- Within the 6 month duration of the
Fiancee visa you must get married (so you'll have to give notice 15 days or more prior to the day you plan to get married, the link above explains all that)
- Before your visa expires you must apply for and off docs (I think they have to be postmarked before the last day of your visa) for the
Spouse visa, aka
FLR(M), aka further leave to remain
-The
FLR(M) will allow you to remain in the UK for a further 2 and a half years, but you can work and have a
national insurance number and all that
-After two years you can apply for
ILR (indefinite leave to remain) which will allow you to stay in the UK indefinitely.
If you plan to go back to the US sometime right after you're married but before the 6 months are up, the order of events are:
- Apply for
Marriage visit visa (also has a 6 month duration)
- Once received leave for UK and get married within 6 months (same as above)
- Before the end of the 6 months, head back to the US and apply for the
Spouse visa, aka
FLR(M), aka further leave to remain
-Once you receive this you can head back to the UK and start work and apply for
ILR in 2 years.
Option A: costs around £1300
Option B: costs around £770
I did the second option because I had planned to go back to the US within the 6 months anyway and DH and I had a second "wedding" over there for my friends and family.
Anything that is in bold above you can search on this forum and find tons of information. There is some old stuff, but there is a massive amount of new info too, you've just got to take the time to look.
Either way good luck! It can be a very stressful time. I hope the best for you!