In reply to Xharlie:
At the risk of stating the obvious: you may be in a situation where what you want is an ambulance and NOT mountain rescue - a few months ago I was at SY and partner mashed his finger. There was no problem about walking back up to the car park and we specifically did not want anything more complicated than an ambulance. So in that sort of case when asked "fire,police or ambulance" it's worth stating very clearly that even though you are at a rock climbing venue you only want an ambulance and will meet in the carpark.
The folk on the phone had a bit of trouble understanding where we were: it may be worth saying "Symonds Yat car park, on the road from Christchurch to Symonds Yat East, on the left before the road starts going down the hill."
I hope you have a lovely time and that none of these things will happen! I have spent many happy hours at SY, and there is even a tea shack where you can get a really splendid lunch or all day breakfast. Mmmmyum.