It's from Reed Wellbeing, which is apparently providing pre-diabetes courses for the NHS
healthieryou.reedwellbeing.com/
It's possible that either you or your husband have had a pre-diabetic blood test result in the past and they've been given your details by your GP.
Personally, I'd ignore it and ask about it next time you go to the GP, especially as your husband is about to have a blood test. You could always ask for a blood test for yourself.
Even if you have pre-diabetes, the course will tell you what you probably already know: lose weight if you're overweight, do 150 minutes of exercise a week, watch your carbs, stop smoking, etc.