UK cabin baggage rules: stricter than you might expect

Budget airlines flying from UK airports, such as Ryanair and easyJet, only include one small "personal item" (bag under the seat) in the basic fare; a full-size cabin bag in the overhead locker is a paid extra, and the free personal item's dimensions are strictly enforced with sizing frames at the gate. Check your specific airline's exact allowance before packing, since it varies more between UK budget carriers than most travellers expect.

The 100 ml liquids rule at UK airport security

UK airport security still enforces the 100 ml liquids limit per container, all fitting in a single transparent bag, for hand luggage, even though a few UK airports have next-generation scanners that lift this rule locally. Since the rule can differ airport to airport during the transition period, pack liquids in your hold luggage if you are not certain, rather than risk having them confiscated at the gate.