My father keeps talking about a one-off drama, but he can't give me concrete details or a title...
The story is about a SciFi/Fantasy author who is in a Coma and has entered his own fantasies. A doctor is somehow tasked to get inside his head and enter the author's fantasies in order to bring him out of the coma. The doctor succeeds in entering the dreams of the author but has to take part in the fantasies as only by winning through in them can the author come out of the coma.
Since dad had a B&W tv until the mid 70s, he isn't sure if it was in colour or not.
The only thing he is absolutely sure about is that there was a sequence when the doctor and author were described as:
'Crossing the Burning Plains of Thoth'
To me, a lot of this is similar to a film called 'Dreamscape' but dad assures me it was a TV programme
I believe you are talking about an episode of "Out of the Unknown" called 'Get off my cloud' (season 3, episode 13 shown 1 April 1969 www.imdb.com/title/tt0064367/). It starred Peter Barkworth and Donal Donnelly. Donnelly was the doctor who entered the author(Barkworth)'s dreams. It featured references to Doctor Who, in particular daleks, if I remember correctly.