Have been a few times - mostly we have stayed in one of the Disney hotels - once we stayed in a circus themed one that wasn't Disney and it was not as fun as staying on site.
Always best to look for a deal. We have done buy two nights, get two nights free and we have done kids go free and have done the free meal plan offers.
We priced up the meal plans it they're not worth it, unless you get a deal where it is included in the ticket price - in which case it can be. When we had the 'free' meal plan we got to eat at some of the very expensive restaurants (ratatouille was amazing but normally 60e each for the set menu). Generally the food ain't great and not work what they charge - their pwn fast food burger place is about 16e for a burger, chips & drink meal. There are cheaper options though (this is a place that charge 7e for a biscuit that looks like Han Solo frozen in carbon).
Disney Village has 5 Guys, McDonalds, a pizza place, Starbucks, The Earl of Sandwich etc and pricier Planet Hollywood and Rainforest cafe. There is a petrol station near to Santa Fe Hotel (you can jump on the shuttle bus even if you arent staying there) and they have food, snacks and drinks - or you can go one stop on the train (about 5 mins) to a big shopping centre with supermarket.
Generally cheaper to fly than go on Eurostar (but have done both) -
Eurostar takes you right to Disneyland (they have just stopped the Disney trains so you have to change trains but it is pretty easy and well signposted and the station is bang next to the park). Flying you can either get Magic Bus (pre booked shuttle coach), or we have got an uber before - you can get a train but unless you prebook it is very expensive. We have also drive over via Eurostar (you get free parking if staying at a Disney Hotel) but that was ties in with holidays - a few days in Disney then a week or so in a house in France.
Cost wise I personally get the cheapest deal to stay in a disney hotel - it is part of the experience - your an walk to the park and you get an extra hour in the morning to whizz around and jump on the rides that have the queues (hello Hyperspace Mountain). Our favourite is Sequoia Lodge - it is cheaper than Marvel Hotel & Newport Bay but not noticeably lowe star - Santa Fe & Cheyenne are further out so you rely on the shuttle bus more and they are more basic.
Our favourite is paying extra for the Golden Forest rooms at Sequoia Lodge - you get a nicer breakfast ,free soft drinks all day and snacks at tea time (not the greatest but with a big breakfast and then dinner, they cover you for lunch) - you can walk from there into the parks and dont have to faff with the shuttles.
Cheapest was approx £1500 for the Disney bit (3 adults one child) 4 nights including driving there - that was buy 2 days get 2 free - no food included but we ate as cheap as we could - with one meal out at Rainforest Cafe, the rest was baguettes, MCDonalds, Earl of Sandwich etc.