So, one thing to think of is the cost of parking at the parks. It's $25/car per day. If you go 14 days, that's $350. Add that to the cost of the 14 or 21 day ultimate hopper from the UK and you've pretty much got the price of the annual pass...so you might want to consider getting one or two annual passes for your group. The platinum pass is $894+tax, the platinum plus is $994+tax.
Both passes include memory maker as well, but the photos are good to download for the year that the pass is valid so no having to hurry up to download the pictures.
You get up to 20% off select dining (not sure which dining you are considering but here's a list):
https://disneyworld.disney.go.com/passholder-program/passholder-benefits-and-discounts/
Since you're going during the summer, you might want to do the water parks so I would suggest the platinum plus pass. The others in the group (not sure how many "family" units there are) but one AP per family unit might be a good idea since I would think you would need at least 2 or 3 vehicles.
Then make sure you create
MDE profiles and link to the non-AP holders (if you decide to go that route).