Hi there MaggieW, unfortunately most grocery shopping sites will give you a cashback amount on your first online shop with them, but then not again. So you can't get cashback on your weekly shop, week after week.
It's still worth looking for deals like this and voucher codes off bigger purchases.
There's also ways you can actually earn money online for doing paid tasks which you can then cash out for real money or gift cards at certain shops.
I'm unfamiliar with cashback sites but do all our grocery shopping of around £110 per week online and wondered if I can do this via cashback sites? Can anyone who knows about these things and how they work advise me please? Thanks.