All of the information given in this thread is good. You should supply substantial evidence to prove your commitment to the relationship, and yes photo copies are accepted of photographs and bank statements, however most official documents do require certification.
The advice about photos (not too many) is true - enough to show the time you have spent together - preferably at events-functionswith family and friends - means more than thousands of seemingly random photos. Try to show a time line if events from when you met to now - this is more persuasive than heaps of the same type of photo.
Definitely phone bills are important if you have not been living together for a time (to prove communication) - emails are also useful although not too many again - just some as evidence of some communication.
Statements from Family and Friends about the relationship, the development and current status is useful.
You are correct when you say a child to the relationship is held in regard, it is accepted generally that there is some strength to a relationship where a child is involved as this shows some commitment to a shared future together (this is not my opinion merely what is looked for)....
how do I know this, I was a case officer once and I wish you luck :o)
Kind regards Rechelle Grimson
--