Hi Backontrack...
I too failed my PPL skills test, and I failed it on bl@@dy circuits! I couldnt believe it, after all the circuit bashing i'd done!
Anyway what I do now, every time I fly, is talk out loud, a kind of narration for what I'm doing, be it HASELL checks or "airspeed alive" to talking through my heights on approach.
What this does for me (and the instructor sitting next to you in your case) is reassure them that you actually know what is going on. That way if you are too high/low on approach you can say "I'm too high/low, applying/reducing power/lowering/raising nose etc..."
You would be amazed the difference it made to my confidence, it reassured me that actually I COULD fly, I DID know what to do and it has stood me in good stead for the CPL that I'm doing.
Dont be disheartened, it will probably make you a better pilot, lets hope that you are soon Backontrack!!!!!!!
Cheers
TBL