i used Fedex because the office was close to my fiancee's home, they took 4 days
I sent lawyer certified copies of birth certificate, passport, driving license, car registration, land registry docs. all were good quality color scanned copies. I sent around 45 photo's of us together and with family, plus maybe 60 pages of chat logs emails, screen prints, phone records ect. Our application took 25 days from submission to approval. Try to file you documents in the order they list them, also include a contents page. When you get to the submission office they will ask you if you have photocopies of all of the documentation!!!! We did our duplicates in advance but i believe you can do it at the submission


good luck!!!!
Good Luck