I am also from East Sussex.It will take about 3 hours drive to Alton Towers won't it?Lets hope traffic is on your side.Last time I went, it took me 6 hours as there was an accident on the M25 and major roadworks on the M1.I could be nice not going straight to the park, if you are the driver, so then you can have a break.(Even if it is just 15 minutes away! )If you are an Annual Pass Holder, on boooking online, I would definately go for ERT!Have a great day and I hope All Rides and Attractions are available for you on the day!