Brits heading abroad should carefully check their passports at least three weeks before they travel. Missing certain critical problems could land you with a £239 bill. Travellers must make sure their passports are valid and in good condition before they set foot on a plane. Any problems could see you turned away at the gate. To sort this out, your passport will need to be replaced straight away, and putting this off could prove costly as standard passport renewals can take up to three weeks.