I didn't know about these health checks until I read about them in the paper a few days back. I have never been called in for one and have been aged 40+ for quite some years now.
See below for links if you'd like to find out more.
I asked about the over 40 check-up at the Doctors last year (or maybe earlier this year) and I was told they don't do them anymore unless there are health concerns.
Post code lottery perhaps?