hi there le shed
don't know if i can be of any help, but i'll give you a bit of background, and just shout if you think i can answer any questions!
we're expecting our first littleone in august. i'm still covered by E106 until next jan. we're not linked to a mutuelle. my french is pretty bad.... however, my knowledge of pregnancy wording is now pretty good! we were amazed at being able to find an english speaking midwife and an obst where we live (couserans in the ariege - i think the rough guide call it the sleepiest part of the sleepiest department in france!), so i don't think you'll have a prob.
one thing you may need to find out is what happens as you presumably haven't filled out a 'déclaration de grossesse' form here and send it to CPAM and CAF (they say it needs to be done before the 14th week of pregnancy)?....i may well be very wrong here, but i think that basically the reason CPAM need the form is to note down that from the 5th month of pregnancy all care is free up until 12 (i think) days after the birth, and that CAF need the form to know of the impending birth and so (hopefully) send you a nice big amount of money in the 7th month of preggie and allowances after the birth.
if you do decide to come over, take your E106 to CPAM asap to get registered with the french system. it took about 8 weeks for them to send us an attestation with our social security numbers on, and although it doesn't seem to matter (because we can show the attestation when needed), we still haven't received our actual carte vitales yet!