Yes it was at Biggin Hill, and it was well worth it.
Reddo makes a pretty good point - my over-riding impression (as a low low hours student) was that I was amazed at just how heavy everything felt compared to a light aircraft. Not surprising when you think about it; a Nissan Micra is going to handle differently to a bus.
If you arrive for a sim-assessment having never flown anything bigger than a Seneca, I'd imagine you'll be in for a pretty steep learning curve. If you already have some sim-experience then perhaps that curve won't be as steep.
All depends what they are looking for I suppose.