It's different with every hospital. I was living in Surrey when we went for my 12 week scan with my daughter. There they make you pay £3 for a token. Each token gives you one scan photo, and you are only allowed a maximum of three photos, no matter how much you're willing to pay for more tokens.
I bought the full allocation of three tokens (£9), expecting to be given three pics, but I went away with six; the lady told me not to tell anyone though; I think she printed too many by accident
The 21 week scan was the same; I bought the three tokens, but the lady accidentally gave me the entire file full of all the photos they took from the scan, so I had about 30 pics; but mostly of her skull and heart measurements - not really something you would show to people, lol.
The photos we got for our 12 and 21 week scans were all photos, not discs. I have a scanner and I scanned them into my computer. Most people do just take a photo of the picture and upload it to the internet, but if you know someone with a scanner, it's a much clearer picture. For our 4D scan, which we went private for, we got a DVD of video, which we had to make snapshots of, because there were no actual still photos.