I have been to Sherwood & Whinfell.
Both were fine. If I had to pick, probably Sherwood was slightly better in terms of layout/hills.
If you are going to hire bikes, get the Flying Start Package. It's about £10 more than hire alone but you get:
2 x Adult Bike
1 hour early check in
Sherwood had a dedicated queue
Groceries in the lodge for arrival - milk, tea, coffee, wine, lemonade, butter and a few other bits & pieces.
For food shopping, the supermarket is quite pricey but if you go about 5pm, they start reducing prices of the meat so we picked up bacon/chicken/mince quite cheap.
When we go, we will eat out once a day then cook for the other two meals to keep the price down as the restaurants are expensive.
ETA: Incidently, the CenterParcs in the Netherlands was cheaper to go to the one in the UK, in a VIP lodge in the Summer Holidays (including cost for ferry)! Might be worth thinking about.
We looked at May half term this year and it was £900 for a comfort lodge in Whinfell Monday - Fri. It was 600 for a week in a VIP lodge (fresh breakfast rolls delivered every morning, most activities free) plus £200 for ferry.