It's a late-November morning and my local walk-in sexual health clinic in South East London has been open for just shy of 30 minutes.

Despite the early hour, there is already a waiting list of 25 patients, of whom many sit filling out forms dispensed by the two receptionists at the front desk.

Others sift listlessly through this morning's Metro, or are absorbed in their smartphones. There is that odd mix of boredom and trepidation that defines most medical waiting rooms.

Having filled out my own particulars, I am called to see a nurse some 15 minutes later; it's a lot quicker than I was expecting. Introducing herself as Sue, she is open and approachable, asking if there is any specific reason for my visit, as I sit down in a small, discreet office.

A check-up, I reply. I am then given my options. I can either wait to be tested on site - "in the hour, if you're really lucky" - or I can take a self-testing kit home with me right now. I waver and ask for a recommendation.

"Unless you're really concerned about something, you're best off taking the kit. Most people do - it's a lot easier."

How reliable is it?, I ask.

"As a reliable as the tests we do here," answers Sue, "and it's free."

Kitted out

I agree on the kit, which can test for chlamydia and gonorrea (through urine samples) and el VIH y sífilis (using a very small blood sample from a finger prick).

"All you need to do is send in the sample in a pre-paid envelope and you get your results in five- seven working days."

If I were to wait to be tested on site, it might take even longer to receive my results, adds Sue.

Within five minutes, I have registered for a DIY sample kit on one of the two iPads by the clinic's entrance, before taking receipt of a small box-shaped package at the front desk. A receptionist throws in a paper bag of condoms for good measure.

I time my visit at just under 30 minutes. It is as painless as I was expecting it to be painful. I also appear to have timed it just right; the waiting list is now well into the 30s. I ask the receptionist if it's always this busy.

"Busy?", she chortles. "This isn't busy. Last week, we had 60 people waiting in here. It used to be quieter but they closed down the other walk-in clinic, so we're getting something like double the patients."

The mention of clinic closures is a salient one.

Government spending on sexual health has been under scrutiny of late. According to a report earlier this year by think tank The King's Fund, funding for services has fallen by £64 million - or 10% - in the last four years, and is set to continue its downward spiral by £30m in 2017 alone.

"Sexual health funding has been the victim of savage cuts over recent years, which has reduced access to testing," says Isabel Inman of Brook, the charity specialising in sexual health and well-being for under-25s.

"We urge the government and local authorities not to ignore these worrying trends. It is a reminder of the real need for dedicated young people's services, which are being compromised by the drive to commission seemingly cost-effective, all-age services. In the long run, this will cost more than it saves."

If the figures are to be believed, now certainly isn't the time to be making cuts. By Public Health England's reckoning, there were approximately 420,000 sexually transmitted infections (STIs) reported in 2016.

While down by 4% since 2015 - when ITS stood at 437,000 - syphilis rates are now at their highest since 1949, experiencing a 12% uptick between 2015 and 2016.

Another major worry is the growing threat of antibiotic resistance discovered in chlamydia and gonorrhoea.

The latter, in particular, has caught the eye of the World Health Organization, which last year called on countries to update their national treatment guidelines and replace older, cheaper drugs proven to have lost their effectiveness in combatting the infection.

"Over the last few years, we've seen a rise in antibiotic-resistant gonorrhoea, which is a real concern," says Bekki Burbidge, deputy chief executive of the Asociación de Planificación Familiar (FPA).

"If you are diagnosed with gonorrhoea, it's really important to take any treatment you're given exactly as instructed."

While sex may no longer be the taboo subject it once was - in the UK, at least - our understanding of STIs is still left wanting in some cases. Myths - ranging from the benighted to the downright ludicrous - persist around intercourse.

According to a survey taken by Brook at a recent university freshers' fair, the following fallacies are still doing the rounds among some younger people: sperm 'sleeps' at night; women don't get pregnant if on top during sex due to 'gravity'; and it is impossible to become pregnant standing up.

"This is evidence that young people deserve access to information," says Inman.

The most common myth around STIs might be less risible, but certainly far more insidious. This is the misconception that a test is only warranted if there are symptoms.

"One commonly believed myth is that if you don't have any symptoms of an STI, then you don't need to get tested," says Burbidge.

"But it's actually very common not to get any signs and symptoms. For example, more than two in three women, and one in two men, with chlamydia won't have symptoms.

"So getting an STI test, if you've been at risk, will let you know whether you've picked up an infection and need any treatment.

"Most STIs can be 'treated easily'," Burbidge assures, "but that doesn't always make a trip to the sexual health clinic any less daunting." For those steeling themselves for a first visit, "it's fine to take a friend with you for support if you want to," she says.

"And don't be afraid to ask as many questions as you need to."

Christmas is almost upon us - that season of goodwill, parties and indulgence in everything from mince pies and mulled wine - to, in some cases, unprotected sex.

According to Brook, its clinics see a third more people in January, as a result of people 'having fun over the festive season'. Sue, our nurse in South East London, confirmed a similar observation:

"Around the two weeks before Christmas, it actually gets quieter round here - people don't have the time to be tested. Then we're busier than ever at the start of January."

To avoid any unwanted gifts this holiday season, a visit to one's local clinic is a smart move. It's not as painful as you might think.