I've been a childminder for 3 years and I am giving it up at the end of this month.
You need to contact your local council who can advise you about the starter courses which ususally take place over 6 weeks, they advise you of what you need to do.
Childminding is not for everybody - initially I loved it, but after a while the problems with parents/late payments/on occassion some difficult children/all the endless amounts of paperwork has finally gotten too much and I just dont want a job that pays me so little for what we are expected to do. It can be financially rewarding - the more children you have the more you get paid but in all honesty having 3 under 5's in the house and some after schoolers is not my idea of a good time! So if you take the average of £3.50 an hour for 1 child to earn £150 a week - you would need to work 50 hours. obviously if you have 2 children full time on the 50 hours you would make £300 a week minus expenses. To be honest I did it for a while with 2 full timers and 2 part timers plus my daughter and I found that although I am around to be with my daughter, she was still receiving limited attention because of being so busy with the others.
Im not trying to put you off, you just need to have a real love of children 'other peoples children' and not mind your evening consisiting of paperwork. the new EYFS has ruined a lot of the fun in childminding for me, its all become so regimented and having everything recorded and monitiored - imo children at this age should be learning through play and enjoying activities without being monitored on their academic abilities.
I'd research some childminding forums- always very helpfull and full of information and they should be able to give you heaps of advice
xx