Yes—two UK services explicitly offer this:

- **[Leftover Currency](https://www.leftovercurrency.com/exchange/zambian-kwacha/)** accepts Zambian kwacha banknotes. Select your exact notes online to see the payout, then post them in. It offers payment by bank transfer, PayPal or cheque through its [postal exchange service](https://www.leftovercurrency.com/how-it-works/).
- **[Manor FX](https://www.manorfx.com/product/zambian-kwacha/)** offers ZMW-to-GBP exchange. Its bureau is in **Datchet, near Heathrow, SL3 9EG**. Call **0800 030 94 99** to confirm acceptance of your notes and the quote before travelling. [Contact details](https://www.manorfx.com/contact-us/)

For roughly £45 worth, I’d start with the online valuation and factor in postage. Check the exact note design: different series can have substantially different buyback values.