@Murderino my 12 week scan I was 13w 2days so it's not strictly @ 12 weeks so to speak.
If you have a Midwife or GP appointment before you hear from them maybe ask?
My 12 week scan was actually booked by my GP (along with a consultant referral) when I went in about a thyroid issue - so they do (certainly in our trust) have the ability to get the ball rolling.
I wouldn't worry to much thought every trust is different but as long as your 'in the system' I'm sure youl hear pretty soon.