Cheers pete, may go for the soft or medium one this time then,
Bowthruster, it's really simple just use loads od lube and don't press on too hard. Have a look on youtube for ways of doing it.
I like using the bilt&hamber stuff as can use it with water, being paranoid about scratching the car I use a hosepipe on trickle wet an area on the car about a square foot then just rub the car with clay, always go in same direction. You'll feel it stick on the particles and after a couple of passes it will be smooth as silk.