Just had the Hypermotard MOT'ed at ProBike in Chelmsford and wanted to recommend them as a really friendly place.
Although they are primarily a rider training centre, ProBike also do MOTs. They are even able to open on Sundays from 8am if you book in advance!
MOTs are just £25 and there is a waiting room with comfy sofa. There's always a burger van outside as well
You can find all the details here: http://www.probiketraining.com/