I agree that planning a visit to the parks has become much more complicated. The dates are good, but it's going to be a lot of money no matter what.
Tripadisor's Central Florida Forum is frequented by a lot of UK visitors who make multiple trips for 2+ weeks at a time. Some are newbies but others are veterans. I encourage you to use that forum as a resource.
http://www.tripadvisor.com/ShowForum...a_Florida.html
On the subject of lodging, Travelzoo often has some excellent hotel deals.
http://www.travelzoo.com/hotels/orlando/