I managed to get mine by using a mini digger on private land. The office here in Bournmouth wouldn't hear of it though. They insisted that it had to be done in a road legal vehicle with roundabouts and traffic lights involved.
But I went over their heads and spoke to the chief guy in Dorchester, who agreed that in my case he would except the mini digger option.
The examiner wanted me to drive around a fictitious road system for about 1/2hour. I think you would have to be very unlucky to fail the driving part. But remember you will need to know the highway code inside out.
It's a bit of a grey area and as Adrian said the criteria can alter throughout the counties.
And Richard as long as there is room the examiner will ride with you in the vehicle. You might like to look at a place such as this.
www.svtraining.co.uk
Ron