Thankyou everyone for your words of advice!!
My back/shoulders and arms tend to tan the most, but I think this is because I have them out in England when it is sunny so they are used to it. My legs (which usually hide under leggings or jeans!), tend to go pink. I think I need to get my legs out and used to the english sun before I bombard them with the blazing brightness of Zante.
I think the idea of changing the SPF factor through the course of my holiday sounds like a good idea. I will be keeping a relitivley high SPF on my face though, I'd rather fake tan it then risk more wrinkles