As above, the perrin will work, as will several others,
http://www.ebay.co.uk/itm/AEM-Turbosmart-boost-controller-solenoid-control-valve-/110794290646?pt=UK_CarsParts_Vehicles_CarParts_SM& hash=item19cbdab5d6
or cheaper but the same i think....
http://www.ebay.co.uk/itm/Gizzmo-IBC...item336fa329a1
The ecu mod is pretty straight forward too, transistor (tip121 will work well here), protection diode and a resistor, you may or maynot need a pull up resistor too. Similar to the idle circuit. Some ecus come with this as standard so check when you buy.
Rob,