Rally driving doesn't run on a normal circuit like formula 1. Instead, but instead it runs ao a cross-counret track, fininsheing in a different place from where it started. Usually each team is made up of a driver, and a co-driver, who reads the map and shouts out instructions, allowing the rally car to cover the course at breakneck speed. On rally driving experience days, you'll be driving, with a professional there to keep you under control.
Rally driving has two main types - road rallies and stage rallies. The vast majority of professional rally driving now takes place as a stage rally, judged on how fast they can drive over stretches of road closed. A team wins a rally either by driving accross the course in the fastet time, or by keeping up with or beating an ideal journey for each stage.
Usually a rally takes place over asphalt roads, on roads that have been closed to the public - These cars cover the countryside at over 100 mph so you can't have any other traffic, but the courses are often lined with fans, hoping to get a closer look (but not get too close!).
Usually, rally driving experiences are on existing rally tracks - not the professional standard rally courses, but often country roads on private estates.