My sister bought me one of these for Christmas and have used it a couple of times now but on the instructions it says the high setting cooks food in 7-8 hours. I put my chicken legs in the slow cooker at around 11.30am yesterday morning but by 5pm, I would've said they were cooked. Same with the beef casserole steak I used last week. It seems rather quick and if the high setting says it takes 7-8 hours, how long would the low setting take??

This slow cooker does run hot, so I would say Low would take 7/8 hours. It depends on what you cook, small items like chicken legs or casserole meat cook quicker than, say, a piece of gammon or brisket. When I had the Tesco SC I found High to be much too hot for slow cooking, except to get things hot in the first half hour or so, then turn it down.
Hope this helps.

We use the high setting just to heat it up the food then turn it down to low. It does run very hot and even low would be high on some slow cookers IMO

Can anyone recommend me a recipe book for slow cookers?

Does all meat have to be browned off before placing in the slow cooker?

Should the contents of the slow cooker be covered with water whilst cooking?

I only use the high setting for half an hour or so to get it started. If I'm out all day it will be on low for the entire time. I rarely bother to brown the meat (another pan to clean)