So I got some warm water and put some mild washing up liquid in it (just a tiny amount), and used one microfiber cloth to wash it down on both sides (had to disassemble the tv of course and remove the front glass, front plastic cover and back cover).
Once washed, I buffed it with a dry microfiber cloth. Seems to be ok. I cannot see that it has damaged the coating any more and all the mould is gone and the grime. Now, the tiny spots where the coating has deteriorated are more easily visible because it's clean, but they have not gone worse.
Anyone know how to completely remove the rubber coating on the back case? It was probably once quite a nice finish, but it's gone sticky with age. I got a bottle of isopropanol but it's probably not pure, so it didn't do much. If IPA is the only way to go, then i'll have to order a bottle of 99% pure.