Well We married in Phill and like all the others say it was cheaper by miles than the equivalent in the UK. Also your family if they are able can come out to the wedding but its unlikely your girlfriends family can see their daughter married in the UK unless they able to obtain Visas to the UK.
Written Letters are not a must, like you we wote emails which we put in the file a few in from each month as examples. We had a few Cards (birthdays valetines and the like) we had sent one another and receipts of Parcels we had sent between us both. Plus Phone bill with sms, alpha telecom phne bills listing calls and logs of yahoo we also used skype sometimes although we did not show the logs from them but im sure its possible to screen shot the chat session logs files and print out to add to your file.
With regards to what Anne would do here in the UK, have you thought about her job skills? Whats her English both spoken and written like? Now is the time for her to work on her English Skills. Firstly for any Interview she might have to have with the British Embassy, at present many people are not having to have an interview to obtain a Visa but that of course could change as the Procedure has changed several times since i have been in a relationship with my Wife.
My Wife now has a job in a coffe shop in the london area, but due to the mass influx of cheap labour from around the world it is now much harder to get a basic service industry job in many areas of the UK in the last few years. My Wife was lucky and also the Manager noted her English qualifcation and skills helped get her postion, as well as some very basic work experience back in phil. Studying for an Ielts is fairly easy with the aid of a few books and cds or mp3s and my wife found watching the BBC world service as often as possible. She took the Exam in manilia but its possible to take in various locations around phill.
My Wife sat on a table with a guy trying to get an ielts level six pass so he could obtain his Visa for Aus. I think both Austriallia and canada already require a certain level of English qualfication before you enter the country who is to say in the future this will not be brought in by the UK?
Do invest in broadband for the family in phill both while Anne is there and other as it will be far cheaper to pay both of your broadband bills both in the uk and phill than have a huge Phone bill erach month.
Good luck whatever you both decide, may i wish you all the best for the future