Here's my (our) experience of getting the ILR.We applied usng form Set O as ours was a case of WP-->WP Exte--> Tier1.
Reached the Homeoffice before time but was allowed only 30 mins prior to appointment.
1) Security Check - Airport Style.
2) Initial Form Check - By security guard
3) Detailed Form and Passport Check by Officer at the counter. Stamped the payment page of the form as "Valid" ,gave a small token chit and asked to proceed to floor 1 for payment.
4) Payment made- Receipt received and was asked to wait for the token call.
5) Waited for around an hour and then was called at one of the counters.
Couldn't really understand the sequence as I guess they call based on the type of application.
6) At the counter- a) Do you have your P60's? b) Have you got photocopies of payslips and bank statements ( I guess case worker was more interested in gettting his file in order than checking mine!) c) Co Hab Documents photocopies. d) Child birth certificate ( green one)
He then asked us to step back and wait.
7) we could see him punching data in his systems and looking at all docs. In particluar the payslips and bank statements , he was probably coraborating the salary.

9) He called me (hand wave signal) again and said to have a seat. He told evrything is fine and "You will be granted...., do you want to know your scores in LIUK"? We said yes, He asked again "How much do you think each one of you got?" and then said I got 23 ( do I care!) and my wife got 24 ( she's good when it comes to reading lol!!!)
10) Waited for another 20 mins and got passports back.
The documens I was asked:
a) 12 months Payslips - original and Photocopies
b) 12 month Bank statement - Original and photocopies
c) Cohab documents
d) Child Birth certificate(green one)
e) Form
f) Photos
g) Passports
h) P60's
All done. Excited on getting the Visa sorted but now have to pay the credit card bill which has swollen with 2700 GBP. Any one has spare money?!!!
Cheers!