UniSarah, re time between changes, the mooncup holds about 25-30 mls. The easiest way to tell how often you need to empty it is to check when you go to the loo, you will soon learn how often is the right interval for you.
I wasn't warned about not using tampons when I had a coil inserted, so just carried on using the mooncup as well Logically I think it must be less likely to cause a problem than tampons, as perhaps the coil's strings could get tangled in the cotton of a tampon, but strings wouldn't have anything to get caught on with a mooncup.
You can buy Mooncups at Boots, but they seem to do sneaky things like put them on the lowest shelf, two inches off the floor - they must really want to sell us all the other gear they have there, LOL. You can also buy one online.
The leaks that posters have commented on - have you tried rotating the mooncup after you have inserted it to ensure that it has fully opened and sealed?
There is a mooncup website, if you have anymore questions or comments they can be emailed. mooncup