alex
I have a palate drop which is somewhat similar but not the same as an obdurator. I do not know if the UK has something similar to a prosthodonist (actually a maxillofacial prosthodontist which is a sub specialty) here in the US. It is a dentist who has had additional training and degrees in making obdurators, palate drops and other prosthetics from dentures to artificial facial components like noses, eyes and so much more. The problem is that here in the US, any dentist can legally make one. Of course any surgeon can do an operation also, but it usually works out for the best if you have your oral appliance made by someone who specializes in such and moreover is familiar with oral cancer.
Here is a summary of obdurators on the OCF web page
Obdurator OCF I'm sorry I cannot help more.
Charm