Childcare.co.uk
Go on Facebook and type in your area, childminder. E.g, Streatham childminders.
Ask in your local fb group. I have found childminders gather at community playgroups and nerby playgrounds. There you will also find parents who can tell you about someone.
Thank you I go to the playgroups at the children centres (Merton) never seen a single one there just mums and babies lol
Have a look on childcare.co.uk a lot of them will be on there and they will have updated their availability etc on there too. Much more upto date than the council lists