Considering the Disney ticket is so pricey, I've decided to buy the Seaworld pass (2 days) for £95, and the 2 day/3rd day free Universal/IOA pass for £164, making the tickets just £259!
We will go to Magic Kingdom after purchasing a single day ticket at the hotel. Obviously we'll have spending money too, so could well (most likely) decide to go to MGM for the day too. I do love that park!
So that will knock at least £300 off.