I have recently found BBC HD 1080/50i rips of the “TV” version on UseNet. All of which have a 5.1 AC3 track. Might be useful if you’re still trying to put together a complete, full-length version.
The reason I thought this might be beneficial is because all Blu Ray releases of Back to Earth are converted to 23.96fps despite originally being shot at 1080/50i. The only downside to to the BBC HD versions is the logo.