Skyscanner for flights. Gatwick usually the cheapest but you will need to factor in an overnight stay. Rent a property in Orlando. Cost in mid season is around £700 per week (if you can find one as they usually get booked up long in advance ) but more in the high season. Park tickets are not normally discounted but some property renters do have links to ticket agents where discounts can be obtained but not normally for Disney. For example I got Sea World tickets for $10 dollars each from an agent in Celebration. Multi park tickets might be the best option. Rent a car before you leave home as that is by far the cheapest option. For convenience I use the airline as that is competitive but not always the cheapest as the airline allows multi drivers free. Shop around. The holiday for 10 will be expensive and made worse by the currency depreciation. Don't forget to get your ESTA form for each party member.