I love riding in Europe as well but as far as this event goes I'm for keeping it in the UK - that way more people will be able to participate - those who can't do the entire thing will be able to do bits of it when we're in their neck of the woods.
plus we stand a chance of getting decent rates on hotels if we're staying places overnight - hotels sometimes offer reduced rates if you arrive in a group and/or are doing something charity-related. we could certainly organize that if we did the event in Europe but it would be more complicated.
and finally of course if we do it here we will have the delightful English weather to enjoy