Hazey the comment is quite accurate though sadly.
I don't know how much experience you have of Downs Syndrome or other genetic conditions, op, but the experience I have is not the one described there. My own ds has a genetic condition (despite his very low risk NT scan - genetic testing pre birth does not uncover all genetic conditions) which is very similar to Downs Syndrome, he is funny, clever, gorgeous, popular at school, and very, very loved.
..it has to include abnormalities as that is somewhat the most valid reason even going right up to birth.How traumatic would that be if only found in the last few weeks, which is why they offer it so early.
Often if genetic abnormalities are found, it is not a black and white situation, unfortunately decisions have to be left until later in the pregnancy, due to the lack of clarity.
Op, you are understandably worried about your pregnancy, and you definitely should call and try to rearrange your scan. But your damning of the NHS is, IMO, a little overblown. I have had much experience with the NHS, some of which has been amazing and some awful, it is a vast and complex institution, it would be incredible if there weren't flaws. But the basic premise of the NHS - free at the point of service - does make it a valuable thing.
I have online friends in the USA, who have just lost their son, the medical bills they now face are overwhelming, leaving them in a position of having to try to fundraise to cover bills and pay for a funeral, at the time of their deepest grief.