If the Childcare qualification is from CACHE (who do a lot of the childcare courses these days) then you can check the Certificate by calling them on 01727 847636. CACHE Qualifications Check website
You can also use the DFES website to list suitable qualifications for jobs in childcare.
A qualification such as CACHE Diploma in Nursery Nursing, or CACHE Diploma in Childcare & Education is Level 3. Newer qualifications are typically NVQ linked, so makes it easier to know the level.
Juicychops, not sure what you mean by Fully Qualified. As Bobkerz says, a Registered Childminder does not have to have done any childcare course beyond the ICP, though many do either have a higher level qualification or are progressing with further training. Talk to prospective childminders about their training, I'm sure they will tell you all about what training and experience they have. Remember also that Experience counts for a lot so don't rule out someone just because they don't have more than the ICP, they may just not be good at exams (like me).
With regard to registration of childminders, all Childminders caring for children for more than 2 hours per day must be registered. In England registration is by Ofsted. Scotland by the Care Commission and in Wales it's by someone else (whose name I have forgotten!).
The registration certificate can be checked by making a note of the Registration Number and calling the respective registration authority's helpline. In Ofsted's case, 0845 601 4771.