4K Amazon Firebox £59.99 at Very when you use code LAMJA at checkout. Far better than the Firestick as you can hardwire with ethernet port and add a memory card. You can also add it to BNP later for 6 months interest free for existing accounts. Unsure if account specific but worth a try and worked for me.
I know Very can be difficult with their cashback but this gets credited instantly as ive just done it. Cheapest ive seen it.