I have done exams at both venues and i would say , Silsoe every time(and not just because the local pub has the best looking barmaid in the world)but , as has already been said,everything is all on one site.
No worries about traffic jams or cars not starting etc.
You can get up, walk over to breakfast (included in the price), wonder back and squeeze in that all important last minute cramming in the comfort of your room.
For me the less self imposed stress on the morning of an exam the better.
Best of luck wherever you decided to go.