Can I go on roller coasters after back surgery?

I'm supposed to be going to Thorpe Park next month for my hen do. I had a spinal fusion done at L5/S1 3 years ago and was wondering if I'm able to go on roller coasters? I can't contact my consultant who did the operation as he was private and I don't have health insurance any more (or the money to pay his fees!) I spoke to my GP today and she said that it should be ok as it's been 3 years and that I should take it slowly and keep an eye on any pain. Has anyone else gone on roller coasters after similar surgery?