I did my first one with MSV on a novice day, really enjoyed it. You won't be solidly lapping all day on your first one as the adrenaline gets a bit much and you'll have to rest plenty cos you'll be knackered!
Elvington is based on an old airfield, but the track is properly laid tarmac so you'll just get "normal" wear. First days wear on track will be very minimal, drifting of course a lot more.
I didn't get insurance, as long as you drive defensively, and be aware of whats happening around you, there's very little chance of hitting anyone else. The main risks come from not listening to the car and overcooking a corner due to overheating tires/brakes or being ham-fisted.
Open pit lane days are fine for a first one, most organisers have bookable circuit tuition and it's rare that everyone is out at the same time, and by the time you throw in a few black flags an lunch, you'll get a few breaks!