URGENT HELP REQUIRED juddering pipes when cistern is full?

recently a fault has developed with my toilet, when i flush my cistern it fills verry slowley via a small jet of water at the top of the filling pipe(not sure of the correct terminology), it now takes about 30 minutes to fill the cister.

fault has got worse in the last day or so as when the cistern is full and the float shuts off the jet of water the pipes behind the toilet start to judder very loudly, not sure how long it lasts cos i have shut off the water to the toilet cos i dont want it to damage any pipes.

please help as i am currently filling the cistern with a bucket and it is becoming very annoying.

Wez
July 2007