Not sounding like a spoil sport but i'd recomend getting it done at you local L/R specialist, Having worked in the motor trade for a number of years, including roadside breakdown, Cam belts do on occasion fail preamaturly, even if fitted to the last letter of the book.!!
With a garage you may have some recourse if this happens - warranty on belt, garage insurence etc.
If it fails they tend to go big and be very expensive :?