If you haven’t renewed your passport, and you’re planning a summer holiday, you’ll need to step on it, because you’re on borrowed time.

The Passport Office has been warning for the last month that it’s taking up to 10 weeks to process applications — up from its usual timetable of three weeks.

More and more tales are emerging of people who’ve been caught out and had to cancel their holiday.

It was only while reading one of these stories that it occurred to me to check the kids’ passports for our summer holiday, and the horrible realisation dawned that they expired last year.

Apparently I’m far from alone in failing to renew — about 5 million of us put it off during the pandemic, because when we weren’t going anywhere more exciting than the end of the driveway, it didn’t seem worth it.

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Now we’re all clamouring to get back on a plane again, applications have soared. The Passport Office worked its way through a million of them in March alone — a new record — and still they’re flooding in.

If you’re in this position, you should also check whether you input the old passport numbers when you booked your holiday. If you did, you’ll need to get in touch with the travel company and see how much it will cost you to update them.

If you haven’t booked yet, wait until the new passport is safely in your hands, because the new number will be different.

If you’re travelling this summer, there’s no time to delay in getting the renewal in. The Passport Office says the quickest and easiest way to do this is online. However, their definition of ‘quick and easy’ is very different to mine.

The first stumbling block is the photo. I learned from experience that the best approach is to go to a photo booth or a shop offering a digital code.

Your photos will be taken in an environment where they’re more likely to be suitable, and getting it right using your own camera is bit of a nightmare.

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It’s worth checking all the rules before you start, which range from having to keep your mouth closed and your face serious, to ensuring none of your hair has strayed in front of your eyes.

Even after checking the rules and trying to stick to them, after 30 photos and three photo shoots, I can vouch for the fact that getting a photo that the online application accepts can be tricky. Even now, I still won’t know if the photos are OK until they have been checked manually.

The Passport Office has also warned that applications will take much longer to process if there’s information missing or any mistakes. It means you need to check all the details properly — one false move when you’re inputting your passport number will set your application back.

It also means you need to get your hands on information that may be a struggle to track down. Not everyone lives in a straightforward nuclear family, and not everyone can easily get hold of their ex-partner’s passport number in a hurry when they need new passports for the kids.

Even once all the paperwork is sorted, you need to find the cash to cover the cost of an application, which at £75.50 for an adult passport and £49 for a child is not to be sniffed at. Unfortunately, if you want to apply using a paper form it’s even more expensive — £85 for adults and £58.50 for children.

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If you’re travelling within ten weeks, you may need to go to one of the seven UK Passport Offices in person.

However, you’ll need an appointment, and you have to be quick to get one, because new appointments are released daily, three weeks in advance, and they’re getting snapped up fast.

Even when you get an appointment — and trek across the country to get there — there’s an enormous additional cost. If you have an adult passport issued after 31 December 2001, you can get a premium appointment to sort everything in 30 minutes, for £177.

Alternatively, you can get a one-week fast track appointment, which can be used to renew adult and child passports, and costs £142 for an adult and £122 for a child. The passport will be sent back to you within a week of your appointment.

If you haven’t checked your passports for your summer holiday, you need to do it now. If they've expired, you can join me in the increasingly anxious wait to see whether they arrive in time.

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• Sarah Coles is a personal finance analyst at Hargreaves Lansdown and co-presents Switch Your Money On podcast.