Buying directly from IKEA is the most straightforward method:
In the UK, you can buy IKEA gift cards directly from IKEA or through several authorized third-party retailers, both online and in physical locations. Direct from IKEA where can i buy ikea gift cards uk
You can also use multi-retailer cards that are redeemable at IKEA: IKEA Gift Card | Giftcard.co.uk Buying directly from IKEA is the most straightforward