it can seem such a tie - feeding to sleep. If you want to stop it you need to break the habit, gently, and replace it with something else. It requires patience. But it might be cuddling, lying with your child, or a book and drink of wanter before bed.
However, remember, many mothers of breastfeeding toddlers feel they have a true gift - the power to put a grumpy and tantruming toddler to sleep in 10 sucks - then you can get on with your life. It's not to be taken lightly!
Elizabeth Pantley has a "No Cry Nap solution" book you might find useful