Hi Tasha,
My understanding is that most UK clinics have small banks of donors who they have basic information about (height, race, hair and eye colour and maybe job and hobbies).
The alternative is to select your own donor from one of the big sperm banks and transport the sperm to your clinic. I think all UK clinics will accept imports from the two big European ones: European Sperm Bank and Cryos. Some UK clinics will also import from USA clinics: California Cryobank, Fairfax and Xytex.
The European ones have quite a bit of info about the donor, including baby photos, a hand-written note and an audio interview.
The USA ones have even more info including adult photos (on some profiles not all), long interviews that really give a sense of personality, essays, descriptions of family members, art/music they had created, etc.
I went for an American one because for me it was important to know as much as possible about the person who will be providing half of my child's genes, and being a curious person I know that if I was the child, I'd want to know these things too. But I do know not everyone feels that way - indeed a lot of people want to know as little as possible!