If you are arriving to the UK, there is a small arrivals shop just after customs with the usual duty free type merchandise, but as you are not taking the merchandise out of the country, duty is payable. If you are in transit, you can use the airside duty free shops.

No, you cannot buy duty-free products on arrival at UK airports in 2026. Unlike some countries (such as Iceland, Norway, or Australia) that allow passengers to shop for tax-free alcohol and tobacco after they land but before they clear customs, the UK requires you to make these purchases at your point of departure or on the plane/ship. Since Brexit, the UK has actually removed "tax-free" shopping for most goods (like electronics and clothing) even for departing passengers, though "duty-free" (which refers to the removal of excise duties on alcohol and tobacco) remains available for those traveling to non-UK destinations. If you arrive in the UK from abroad, you are restricted to the personal allowances (e.g., 18 liters of still wine, 200 cigarettes) that you bought before landing. If you exceed these limits and fail to declare them through the "Red Channel" or the official HMRC online app, your goods can be seized and you may be fined.