Just found this on YBW forum, by skipper_stu:
For info, the cam belt kit which includes the two rollers/tensioner is a Quinton Hazell part, Number QBK459
Some links:
http://www.mister-auto.co.uk/en/timing-belt-kit/quinton-hazell-qbk459_g307_a057QBK459.html?KTypeNr=0 (http://www.mister-auto.co.uk/en/timing-belt-kit/quinton-hazell-qbk459_g307_a057QBK459.html?KTypeNr=0)
Also on Amazon for less, but out of stock: http://amzn.to/WGnZGO (http://amzn.to/WGnZGO)
That's what I used when I did mine. Same as VP kit but half the price.