Look at one of Daves at opentrack if you want to book up a track day. They do a great service, always a brilliant mix of cars from all eras and speed and they also offer free tuition and pictures. Brilliant atmosphere and everyone will help.

My advice for your first one would be take it slow and build up. Dont drive as such to go over your driving limits or the cars whatever comes first. Its fun going fast, but more fun winding it back 10-20% and going home in a car thats in one piece.

Most of all have fun, once you done the first one you'll be booking more!