Dom Joly: Down in the rainforest, something whirrs...

With the help of a hidden Wi-Fi gizmo, our man breaks his I'm a Celebrity... isolation to dish the dirt on Lembit Opik, and feasting on koala

Greetings from deep in the heart of the Australian jungle. Actually, it's not a jungle as there are no tigers or elephants. This is a rainforest, but jungle just sounds better on the telly.

I know a lot of people think that this show is actually filmed in the gardens of the supremely tasteless Versace Hotel, an establishment once memorably described as looking as though Elton John had vomited all over it. It isn't. We are truly in the back end of beyond, the middle of nowhere, and it's really not my ideal holiday destination.

I have managed to smuggle in a small Wi-Fi device and buried it by the creek. This way, unless they discover it, I can continue with my weekly columns.

So what is it like being in here? Well, I've actually had quite a lot of training without realising it. I "served" 10 years in a boarding school with no parole. In there I was surrounded by people I loathed while being forced to live under a seemingly pointless set of rules.

North Korea also comes to mind. I was there last year while writing my book The Dark Tourist. Again, I was forced together with a bunch of strangers and shepherded from one weird experience to another by an overly authoritative minder who confiscated my mobile phone and told me where I could and couldn't go.

So I'm as prepared as I could be for this experience. I suppose I could have done prison time: that would have helped. I've been locked up three times but never spent a night behind bars so it doesn't really count. Of course, none of these experiences can prepare you for the joy of a tick on your testicles or a leech on your buttocks, but I have watched as many episodes of Ray Mears as I can stomach.

Why am I doing this show at all? There are several reasons but the main one is that somebody is paying me to go on the ultimate weight-loss session. I also genuinely want to find out how I cope under pressure. Although I've travelled the globe, often to some very unsavoury destinations, I always try to incorporate a modicum of luxury in my journeys. I'm not very good at roughing it and I'd really like to see how I cope.

One thing I realised in Syria was how rarely we deny ourselves something we want. I was in Palmyra, one of my favourite places on earth, and it was Ramadan. The government minder assigned to us was Muslim and was fasting during the day. The director thought it might be a good idea if I did the same for a day. "Good ideas" in TV generally involve discomfort for the presenter. However, I did it – no food or drink for the whole day while filming in the baking hot desert and being tempted by a full picnic laid out before me. When the cannon went off at sunset to mark the end of the fast, it was a particularly euphoric sensation and it had only been a single day.

Doing I'm a Celebrity... Get Me Out of Here! is a far more intense experience, and I hope that it leaves me with similar euphoria. At the moment, I'm not particularly convinced, but we shall see how things pan out.

I need nothing from this show. I have a two-book deal and a Trigger Happy TV-style film in development. My problem is that I have great difficulty saying no to things. This is an opportunity of a lifetime. The chance to become close friends with Lembit Opik and to eat a koala bear's anus. You'd have to be insane to pass that up, wouldn't you?

The IoS's jungle representative has already joined the bookies' front-runners

At home, he counts Jeremy Clarkson and Liz Hurley among his neighbours. So living with a dozen gruesome minor public figures in the Australian jungle shouldn't pose too many problems for Dom Joly, as he starts life on the set of I'm a Celebrity... Get Me Out of Here!.

The Independent on Sunday's very own man in a bush hat has joined the cast of ITV's latest reality television series as a late-comer to the original cast. He entered the camp with the comedian Jenny Eclair on Thursday, Day 5 of the 10th series, which is already proving an unexpected ratings hit.

In his weekly column for The IoS, Joly reveals that the reason he is taking part boils down to an inability to say no. But the 42-year-old comedian also sees it as an opportunity to lose weight, perhaps inspired by his last shot at reality television. In 2007 he worked as a paparazzo for the ITV show Deadline, which led to Pierce Brosnan calling him a "persistent little fat fuck".

Dealing with the egos of his fellow contestants will be among the hardest challenges faced by Joly, not least as he described himself as "very confrontational" before setting off, no doubt to the delight of the show's producers. Only a week in, the show has already provided plenty of drama. The television nutritionist Gillian McKeith had to be given oxygen by medics after fainting in two "Bushtucker Trials". These are physical tests which contestants must complete to earn food for the camp, and usually involve being locked in dark holes infested with creepy-crawlies.

Unfortunately for Ms McKeith – formerly Dr McKeith, until the Advertising Standards Authority had a quiet word – her self-confessed phobia of rats, insects, heights and enclosed spaces has only encouraged viewers to nominate her for tasks. As it's an interactive show, viewers get to choose which celebrities to humiliate by text message from the comfort of their front rooms. So far, McKeith has had to choose between eating a crocodile's penis and obliging her female fellow campers – Sheryl Gascoigne, Britt Ekland, Playboy bunny Kayla Collins and X Factor finalist Stacey Solomon – to share just one meal between them. She chose the latter. Her performances in every trial have been hysterical enough to ensure the viewing public has reselected her every time.

Last week, bookmakers were naming the contest a two-horse race between 21-year-old Solomon and Happy Mondays frontman, Shaun Ryder. But last night William Hill lowered Dom Joly's odds to 7/1, placing him equal second with Ryder. Prices are based on the public's betting so far, which has seen McKeith attract only £2.57, prompting suggestions she may be the "most hated contestant" ever. It's the first time in I'm A Celebrity history that such a clear favourite has emerged in the first week. Quite why Solomon is so popular remains unclear, though some cynics say her habit of taking long showers in a bikini for the cameras may not be unrelated.

Tom Peck and Matthew Bell