The Honda dealer in Letchworth is very good at giving long test drives (well they did for me, half a day in a petrol Sport, the other half in a diesel ES), but I'm not sure what they have in the way of
CTR demo cars.
The Cambridge area is percieved as being "rich", so dealers do not usually offer much, I doubt the Cambridge dealer will be much better.
I part exchanged, eventually getting to within £200 of my original cost to change budget, but it did mean talking, then walking away, then getting a call to come in and discuss and getting slight improvement on the trade in price, which I eventually accepted.
Terry