I have looked at a bunch of other posts mentioning sessions, and think I could probably get something working bringing the email address into the confirmation page, in a second form. Probably hiding the fields so it just has the submit button.
But I'm thinking this would give an extra record in my database (or a separate table).
It would be really useful if I could get a new field for newsletter signups into the same record which has just been submitted.
The multi-page form methods like mentioned here don't work for me because the newsletter signup I want to be optional - people can choose to click a button for it on the confirmation page, or they can leave the page and continue browsing. The main form's data has to be submitted on the first page.
I hope this makes sense, I am wondering if anyone has any ideas how I could go about this?