If you haven't gotten your spousal visa yet, then when you apply ask for KoL...(Knowledge of Life) endorsement. This means as soon as you enter the UK you can take the Life in the UK test, and if you pass it, apply straight away for ILR.
Documents for the spousal visa...hmmm lol we just went through this last week.
Rental agreement/mortgage papers (UK) Also a letter from the landlord stating you can live at the residence.
UK spouses bank statements (3-6 months)
Either their birth certificate, and a copy of their information page out of their pass port..or their actual passport.
3 months wage slips..or if a new job a letter from their employer stating their wages and job information.
Sponsor letter from UK spouse.
You will need your passport
2 passport photo's
finance information, like banking statements, savings etc.
driving record if any tickets
Marriage certificate
Proof of living as man an wife for 4 yrs outside the UK. (like bills in both names covering 4 yrs..like 2 per yr...or official IRS transcripts)
Your qualifications and/or CV
Proof of continued contact if you have been separated for more than like 3 months. (like phone records, emails or chat sessions)
I may not have gotten this list 100% right, but this is what we submitted for my wife's application last week, and she receive ILE.
I do wish you the best of luck. It is a very stressful process. Just remember if you are in the US, and don't want to wait for weeks..then you have the option of paying an extra $300 to have it expedited.
Good luck