You see, this is the sort of post that demonstrates ignorance...
It didn't even take a great deal of searching : http://www.bbc.co.uk/health/womens_health/issues_smeartest.shtml
I may be reading it wrong but it doesn't say anywhere about it being a legality to get tested.
The onus,however, is on the individual to book an appointment once they have been automatically reminded.
Jade was 27, so unless she wasn't registered with a doctor had received a letter inviting her to make an appointment two years prior to her eventual death.
Also, reminders are sent out every three years, not five.