From your sig it appears that the OA is in your kneecaps? What about the rest of the knee? Cartilage transplants work best for relatively focal areas of damage not widespread OA wear and tear but much does depend on the technique and the surgeon. Repairs on the kneecap have a lower rate of statistical success due to the shearing forces involved but people on here have had good outcomes. You need someone to look at why the knecap is worn out at age 38 though and if need be, perform any corrective alignment work to stop the repair getting trashed at the same time. I think cdubb has a Post Op diary about ACI on the patella and a re-alignment on at the moment.
You could start by looking up ACI and MACI both on here and through hospitals here that perform it. RNOH Stanmore and Oswestry and probably the pioneers, and there is the ACTIVE trial currently running through the NHS for recruiting people to ACI and associated repairs. There are also newer techniques such as Cartifill pioneered by Anan Shetty at the Spire Hospital in Kent and that is quite well suited to patella repairs but is VERY new. (I have consulted with him and its an option for my Grade3-4 kneecaps).
Partial replacements of the PF joint are also developing and provide an alternative to full TKR. Several people on here have had them a young age. Check out posts by KW, snorunner.
Have you looked at visco injections to help the symptoms whilst you research? I have Euflexxa and it works quite well for me for about 4-5 months.
Are you reliant on NHS funding? If so, you'll need to be creative, pushy and resourceful to acess newer technique but it can be done,