They haven't got to the children so far, it seems! Despite the fact that my medical records and those of my husband (such as they are) appear to have been uploaded onto the NHS Spine, and this even though we had requested that they shouldn't be, the existence of non-schooled children appears to have thrown several systems into some confusion. Even in our own GP surgery's database, the children would appear not to exist, though they they were registered there perfectly satisfactorily for a number of years prior to the computerisation! I'm guessing that this is because they aren't on school databases and the mismatch throws the system into confusion.
Very sadly, I don't imagine this situation will continue for long.
However, for another related reason to home educate, read Gordon Brown's woefully inadequate response to Nick Clegg's questions about fingerprinting children in schools, via