Cafe Ark really is the best part of the Sale Water Park visitor centre. It's warm and clean (we visited end October 2014) and the staff are kind and well informed. Service is good and the food fabulous. My friend had their soup of the day (leek and potato) and I had a slice of their gorgeous chocolate cake.
In addition to great vegan food, they also had San Pellegrino drinks which we both adore - in lemon, orange and blood orange flavours. To have such high quality soft drinks really added to the experience.
There were newspapers for people to read and the atmosphere was relaxed and friendly.
We'll definitely be going again (I hope we'll become regulars) and I can highly recommend. If you go, don't forget to buy cake to take away with you too ;)
Cons: Hard to get to without a car, I think