Tried it this morning and worked for me so best of luck.
Not a huge discount but it buying anyhow...
Live from Monday 29th June
Take advantage of £5 off your next purchase above £25
Add the code GIFT05 at check-out.
The Promotional Code may only be redeemed against items sold by Amazon.
Possible selected accounts like last years offer but i'd thought i'd throw it in
Cannot be used on Gift Cards, items sold by third party Sellers (even if "fulfilled by Amazon" or "Prime Eligible"), Warehouse Deals, digital products, e-books, video games that are not yet released, alcohol, baby and infant formula, e-cigarettes (including e-liquids, refills and accessories), delivery costs, or against gift wrapping costs).
The Offer is valid only between 29 June 2020 and 12 July 2020, and limited to 10000 coupons.