Alright, so it costs £180 but for the level of expertise/detailed scan, general surroundings, and complete piece of mind it couldn't have been money (or time... the time!) better spent. Plus £18 parking. Bargain! 
Bottom line - all things they check (duct in liver, heart, nasal bone, nt) were perfect. Well, the nt, it was impossible to get an accurate measurement as the baby had the cord around its' neck like a necklace which was making the nt bulge one side of it and less the other... even when we scanned for an hour, then I waited in reception for an hour (drinking sugary hot chocolate in order to encourage the baby to move) and tried again. As you know my measurement was 2.0 yesterday and he averaged it out to look about 2.1 or 2.2. My bloods, apparently were, and I quote, fantastic.
My risk started at 1:138 age adjusted. After all measurements, it was adjusted to 1:2761 which is the absolute lowest they will give me as they do not lower the risk by anything more that x20. So, as he told me, it could not look any more perfect right now. (oh and crl was ANOTHER day ahead... this baby is getting bigger by the moment - I can see another whopper on the way!)
Further, he recorded the whole thing onto a dvd for me, and printed out three (different!) pictures - two of which were 3D images that he switched to momentarily to show me how the baby had the cord right where we needed to take the measurement!
They are beyond fab at the fetal medicine centre. Cannot recommend them highly enough. THe difference to how I felt yesterday compared to today is like night and day.