Darren,
The inlet valve will have two wires going to it and is normally where you actually screw your hoses on to (this is part of the valve). The valve operates as the timer applies a voltage to the solenoid coil and this moves an internal magnet that opens the valve. When the voltage applied is switched off then the coil is deenergised resulting in the valve closing again but sometimes they stick open regardless and continually fill with water.
Indesit is part of the Hotpoint group and where you obtain this depends on your location/country. Many domestic appliance spares companies would be able to supply this or look at the Indesit or Hotpoint website and order from Hotpoint if in the u.k.
Another company I have dealt with is shown below and if you call them they should be able to assist if u.k.
http://www.partscenter.co.uk/hrpc/default.html
sparky
February 2006