As above posters have said.
There used to be some good guidance, and of course you could even phone the CAA FCL Dept. The truth is that your Examiner will let you know what they expect, ie that you can pass the test!
In my case (dating back just 3 years) I had 7 years self imposed non-flying.
When I needed to get back in the saddle, as they say, I had a sweaty hour upper air work, a very sweaty hour in the circuit, and then the instructor said I was ready.
The Instructor and Examiner had to be different people.
Clearly I'd not forgotten how to drive an aeroplane, but as we all know, it's all about the other stuff that non-flyers don't appreciate. Polish and practice. Even just practising running through the mnemonics for pre-flight, airfield approach, and forced landing are simple things that can make life easier when under stress. Radio calls I find are the first thing to go rusty.
Much of this stuff can be practised on your daily drive to work as you bosh down the M25 or wherever. Your mind is busy with the drive, give it an extra task.