Where should I look to find private land to drive on?

I want my 23 yr old daughter (full driving licence, own car insured) to have a drive of my car - just for the experience - but my insurance company won't insure anyone under the age of 35 (no, not 25) to drive my car, not even for a day. Her policy doesn't allow 'any-car' driving so I want to find somewhere where she can legally have an hour's driving time off public roads. Does anyone know *specifically* where I can find who might provide this facility? I assume that this will probably be a commercial service and I have no problem with that. Searching for 'off-road driving' brings up 4x4 tracks and entering 'driving on private roads' just brings up general legal advice. My car is a saloon, so I don't want any dirt tracks. Your help and advice would be greatly appreciated.