Fancy, I had to move my dating scan forward a couple of days and it wasn't a problem at all. I just said it was because I couldn't get any time off work that week because I was taking my class on a residential trip. (This was a lie, I have to admit, it was DH who couldn't get the time off but I thought they might be funny about changing it for that.) Just phone and ask if you can change the day, I don't imagine it will be a problem. Do it soon though as it will be harder to get an earlier appointment the closer you leave it.
Retro, I don't envy you with the start of term and a new house to sort! I am dreading going back to school tomorrow, I really can't be bothered. Not because I mind going back to the actual teaching part, it is the 2 hour plus commute each day that I dread! Anyway, 7 1/2 weeks to go and that's me as I am not going back after the summer, yay!
What about some re or pshe tomorrow afternoon and a bit of practical maths in there somewhere about measuring? What year do you teach? My class are "designing a game which helps develop time table knowledge" tomorrow for maths... Ie. also doing non written maths so I can get some reports finished and risk assessment etc for a trip.
Poly, are you going to worry if you don't get the NT tests done? If you are, I would personally get it done and deal with next steps, if needed, when you get your results. If you can cope with not knowing, don't get them done. What do you want to do about other checks at 20 week scan at this stage or are you not thinking that far ahead yet?