When the toilet refills you can hear the pipes vibrate and make a noise. I've turned our stop cock to off and then turned it back on slightly and this rectifies the problem but the water then just trickles out. I think it's an air block but I don't know how to check the toilet. All the tapes are working fine.

What you are hearing is water hammer. Make sure all the pipes are secure and strapped. They make hammer arrestors for this purpose if nessesary... You may also want to have your water pressure coming into the house checked to see if it's too high...

Thanks Rick, I've had a pressure value fitted to the in flow pipe for the toilet and all is fine now

Graham