Can anyone please give me any advice on how my partner can addopt my daughter?

My daughter is 2 & has never known her biological father. From the moment i told him i wouldnt have an abortion he stated he didnt want anything to do with the child. He HAS met her as I got in contact with him asking him to see her when she was 5 months old. This contact lasted for 6 weeks! He has now not saw her for approx 18 months, has never tried to get in touch, he actually changed his number when he stopped seeing her & although I believe he is still living in the same place, it is 20 miles away from my home so i am not certain of this and have no desire to look into it! He is obviously not on her birth certificate & he has never paid a penny towards her. I contacted the csa over a year ago but have had no success. Please dont think i am looking for sympathy here, i am simply trying to give as much info' as possible in the hope that someone can give me correct advise on weather it is possible for my partner to adopt my daughter, what rights this would give him and what rights (if any) would her biological father be left with? My current partner is the only father my daughter as known, he treats her as his own & although the truth WILL be broken to her as gently as possible over the years, i would greatly like things as they are now to be as legal as possible. Hopefully someone can advice? Many thanks