I second Worried - I booked a scan with them (they use them for training purposes) and they were lovely on the phone and via email. I ended up cancelling the scan in the end as I got a hospital scan due to pain, but they were very helpful.
Have you tried speaking to the midwife and requesting an early scan. If you've had a mmc before and are worried/stressed then they should offer you one. I got one at 7 weeks and midwife was lovely about it.