As Mikey just said, Asda and Boots have a photo legacy service. They transform they scan the negatives to digital files, which then can be printed (and enjoyed on your PC etc.).
If you want to do more than the occasional negative then get something like this
Amazon.co.uk User Recommendation
It will scan your negatives and store / print them as digital photos.
It would soon pay for itself if you want even a few dozen negs printed .
Are they colour? I took a roll of black and white pictures in the run-up to our daughter's wedding and found that many places couldn't do b and w, but Tesco assured me they could and repeated it to me. When I went to collect the photos there were none, Tesco had misrepresented their service.
^^ Almost all scanners can scan negatives allen, you can get a perfectly usable one for under £40. See my link to Amazon ( or there are 100s on eBay) If you have more than 20 or so negs buy a scanner, once you have used it and done all your negs you can sell it on eBay and get 1/2 your money back!( or buy a used one in the first place and sell that, when you can probably get back more than you paid in the first place)