Another point of view from a nursery nurse! I did all my training for my qualifications once I had dd and was fortunate enough to land a position in a specialised baby unit, where I could bring dd with me. This is still the case now, dh doesn't feel comfortable with me working and dd in another setting, so we have to go together which is ok, but not on the clingy days when I've got work to do!
You need to weigh up the pros and cons of cms and nurseries and pay visits to both.
I prefer the idea of nursery for my dd, interaction with other children in an age/stage appropriate environment, more carers for support etc. You know that nurseries are OFSTED registered and that the staff are CRB checked. You also know that they hold relevant qualifications or are training towards relevant qualifications. You know the environment is appropriate for young children.
On the other side of the coin, however, you do not always know if this is the case with cms. That's not to say that cm's don't have all of these things. I think you just know what you're getting with nurseries.
You should get in touch with your local children's information service for a list of all childcare providers in your area and take it from there. Consider all your options, to make sure you mkae the right decision. You can also ask them for a list of questions to ask when visiting propsective settings. Most CIS places give questions to ask or you might find something on the OFSTED site.
That's another point, visit their site and read up on all prospective settings as this will give you an idea as to the standard of care and education that you can expect, either from a cm or a nursery.
Good luck!