Further to above: A very switched-on lady elsewhere once summarised the procedure (for the LAA Rally, but much the same here) as:
Originally Posted by leiafee. DO NOT USE FOR PLANNING PURPOSES!
1. Fly to Pitsford reservoir.
2. Fly round it in a square until you see a sensible gap between you and the aircraft heading off in front of you.
3. Join on a sort of massively extended left base if it's 03 or a wide-ish right downwind if it's 21.
4. Keep your gob shut unless you're on final or on fire.
5. Park where the blokes in orange tell you to.
Yes, there's more to it than that, but not much and that's the essence. The instructions aren't "massive" if you digest them.