Poor RichieRotten, getting backhanded with just one post.
Now here's the dissenting voice. Slide projectors are passé. More trouble than they are worth and slides do not need "frequent projection to stop them fading". A furphy perpetuated by Kodak long ago.
With this agreeable statement, you're actually taking the high and intelligent road to viewing your work for perpetuity, instead of for 10 minutes with beer and chips:
[...] I am desperate to find someone who can produce high quality scans with the eventual aim of having my photos printed and hanging on the wall behind glass.
THIS is the way to go. I tossed out two projectors in 1998, concentrating solely on printing, framing and...selling (Ilfochrome Classic). I admire your forward plans that bravely transcend this fanciful notion that slides always, always look better when projected, rather than what you can do with displaying prints made to show under spots. That's what the majority of slide-to-print photographers are doing today. Think for a moment about the sensation that was justifiably caused by 3 metre wide Ilfochrome Classic pano prints, defunct now of course; if you can find any in a gallery anywhere in the UK that has these beauties on display, do make the effort to go along and see how they make a bold and enduring statement on the viewer. I'll bet that's what you want of your own work, too.
Re labs. Two years I had some communication with a guy by the name of Boyd in the UK who was at the time experimenting with the continuation of Ilfochrome Classic print production. I'm wondering if he offers the steps you are searching for (which, incidentally was never a part of Ilfochrome Classic printing). I think he is in Essex. I suggest you Google for Professional Photographic Labs that offer A to D services, with a specialist stream of production from transparencies. Just ensure that your slides are well exposed, preferably with a 0.3 to 0.5 stop (+) bias to counter the loss of an equivalent stop at the print stage (you didn't mention what format you are using: 35mm presents its own challenges and constraints while medium format opens up a whole new world). Take along your work to the lab you have chosen and discuss carefully what you want, how and how much you are looking at. You may have to rely on the postal system to send things in and get them back; this is a problem because you need to ready and avail yourself to proofing and close communication. Once you find a pro-lab that works well with you, and you with them — stick to it.