£10 pp pn is excellent value. Have you looked at the prices of other campsites? Where else are you going to get an excellent week end of fun for £20 (OK food and petrol on top)
We will get use of the showers, electicity, water and a landlord happy to have 100 odd bikers on his land!
There will be other stuff provided too but you'll have to wait and see about that
The rideout costs you no more than your own petrol. If you don't want to camp you don't have to. If you want to stay somewhere else, more or less expensive, you can.
Up to you really