Okay, it's not exactly free, but I still think this is a pretty good return on a £1 spend. If you sign up for a 3 month trial at The Gourmet Society via Topcashback you get £3.53 back. Plus big savings on your food bill when you use the card. It won't let me post the link as I'm a newbie, but if you search on TCB for The Gourmet Society it's very easy to find.
Oddly just searching "Gourmet" does not bring it up, but "The Gourmet" does. Something weird there, as "gourmet" brings up others like "Premier Gourmet Foods". Anyway, direct link: https://www.topcashback.co.uk/the-gourmet-society/