I think that your local Childrens Information Service (local council usually) would be your starting point. They deal with the Childminder Application pack - at least in England.
Please research your local area to establish if there is sufficient demand for childminders, as you don't really want to go through the process of registering to then find it very hard to fill vacancies. Find out how many childminders are in your local area, CIS can supply a vacancy list. Ofsted's website will also give you a good indication of number of compeditors, based on your postcode. Look around local shops, church halls, and anywhere else that may permit local advertising, to get an idea of where you can advertise, and also to see how many childminders are advertising vacancies.