Go on to the NCMA website ( assume you are in England not Wales, NI, Scotland ?) and find the details for your local development officer - she will know exactly who is who.
Other than that, can you not call in as a prospective parent and ask to see her certificate of Registration which we are all legally obliged to display prominently?
A CM can legally look after one child under 1, a total of 3 under 5s, the rest 5-8 and over 8 as many as insurance would allow but only if not affecting care of younger children, so it is not unheard of for a CM to have upto 10 I suppose, although I personally do not agree with that.
They may look after more or two babies etc with a variation but a new minder wouldn't get this anyway I doubt, unless it was twins.