Why NHS doctors charge patients for letters
You've sorted your flights, hotel and travel insurance, and dug out the family passports
But if you are more than 27 weeks pregnant (or look like you might be), have had an operation recently or broken a bone, there is an extra bit of paperwork you need to add to your holiday to-do list - a letter from your GP to say that you are medically fit to fly.
It is a requirement of many of the major airlines and without one, check-in staff can refuse to let you board your flight.
The chances are you will not even have to visit the surgery but you will still have to pay for a note from the doctor, who is allowed to set their own fee.
A quick and very unofficial social media poll revealed charges ranging from £15 to £40 from respondents around the UK requiring a basic consent letter relating to travel plans.
Francesca de Franco paid £20 to her south London-based doctor when she flew to Italy while pregnant with twins two years ago.
"The midwife said I might need [a letter] because I was quite big," she said.
"She confirmed I was good to fly on the dates I needed and told the GP, who then sent me a three-sentence letter to confirm that. The GP didn't even need to see me."
Ms de Franco was surprised to be told she had to pay.
"I don't really see how they justify the cost, £20 seems excessive. It was a very standard letter with just dates filled in from the midwife."
Ms de Franco, who runs parenting website The Parent Social, said that some of her contacts had been put off by the cost.
"One lady was charged £30 for a letter - ironically her flights were only £32.99. Another was on a very tight budget, she said that tipped her over the edge and she didn't bother going on holiday."
According to the British Medical Association recommendations, these ladies could have fared even worse.
On its website, the BMA's suggested guidelines for fees range from £16.50 for a "straightforward certificate of fact" without an examination to £124.50 for a "written report without exam, with detailed opinion and statement on condition of patient" which it advises involves up to 30 minutes' work.
So what exactly are you paying for?
Dr Peter Holden is a member of the BMA and sits on the committee which advises GP members across the UK about setting fees.
The reason patients have to pay is because the NHS will not cover the cost of this sort of work, he told the BBC.
"The NHS provides general medical services. Letters for patients for third parties are not a health service," Dr Holden said.
"This is not money into the doctor's pocket. This is the gross turnover of the practice. Who's going to pay the secretary to type the letter? Who's going to pay the receptionist to sort it out?"
The GP is the only member of staff in the practice who generates external income, whether from the NHS or private sources, he added.
"Anything you do that is not part of the NHS, you have to recuperate your time and your overheads from somewhere - there is only one place and that is from the patient."
Dr Holden said it is widely accepted that a GP needs to earn a gross pay of "over £200 an hour" to keep a surgery open, and that writing even a short letter is not as straightforward as it may appear.
"What people forget is even for a one-liner the General Medical Council requires we verify that what we say and sign is true. That means a trawl through the notes to confirm that it's true.
"That takes time. The production of a one-liner can easily take 20 minutes," he said.
However Dr Holden did acknowledge that some doctors do charge too much, and blamed the introduction of the 1998 Competition Act for creating a "free for all".
"Some doctors will be very reasonable and one or two will be overstepping the mark and I do not condone that," he said.
"When the Competition Act came in, we said this would cause this kind of problem. The fact is the government said 'no, it has to be free for all'."
In the event, nobody at the airport asked Francesco de Franco for her doctor's note - but Sean Tipton from ABTA, the travel association, said that it can be an expensive risk to take if you decide not to bother.
"It's certainly reasonable for travel companies to ensure that their customers can travel safely and that's why they ask for these letters - to make sure that is the case," he said.
"All these things are very clearly set out in their terms and conditions. If you ignore those and have just taken a chance and they don't let you on, you almost certainly wouldn't get a refund of your ticket."