Bike ride London - La Linea

Ok got this idea to cycle from London down to La Linea near Gibraltar, and really need some advice on routes, what to expect, if anyone has cycled through spain and knows what this great country has to offer please help us out.
I's gonna be a massive group journey camping on the way, cycling through the wine country in france nad probably hitting every big bodega in spain, looking into touring bikes, my old steel frame bike sadly won't do, so if anyone knows anywhere to pick up bikes for a reduced price that would be appreciated. cheers

-steven