don't take risks, send everything your asked, not worth the money, time and effort to send an app that might get refused
b4 you send anything to your g/f, check and double check you have everything, or as you've found out it can be costly to send anything by courier..
the letter from your landlord approving of your lady staying there is very important, as it's part of the evidence you need to prove you have accomodation for her.
maybe you could get your landlord to write another letter mentioning his first letter, stating that he aproves of you both staying there, and get it scanned. but i'm not 100% sure they will accept it..