you should be fine, weve camped in some right old thunder storms, as long as your not thinking of putting up a tv airel or anything you should be fine, were off on sat , and hoping for good weather, but dont worry about the odd storm youl be fine.
Apparently the safest place to be in a thunder storm is in the car, as it acts like a Faraday cage. However, we've been through three storms whilst camping, and on each occasion, we've stayed in the tent, made a coffee, opened the curtains & sat watching the lightening over the sea - we came through each storm safely and, horror of horrors, we actually enjoyed it