It is 9.30am on a Saturday and the whole family is wobbling through a woodland assault course 25ft feet above ground, hooked into harnesses in case our schoolyard adventure playground skills fail us.
Unexpectedly, my husband, who thinks nothing of hopping on sky-high ski lifts, says he is scared of heights, and threatens to find the nearest ladder down.
"Come on Dad," yell the kids. Aged 12 and nine, they are fearlessly hopping through the trees like squirrels and grinning with enthusiasm. I'm also smiling broadly - a mixture of adrenalin and schadenfreude.
We chivvy each other along to the final platform, take deep breaths, then whoop as, one by one, we zoom down a zip wire, across a lake to the other side.
"That was amazing!" says my husband, now he's safely on the ground. It's hard to believe we're out of bed so early, doing something fun as a family, and - despite the countryside surrounds of lake and trees - less than an hour by train from London.
We're in Woburn, Center Parcs' latest holiday park in Bedfordshire, and the newest family playground for those in the capital. For anyone unfamiliar with the Center Parcs concept, it is basically a sprawling woodland area dotted with lodges; car-free and hosting a range of indoor and outdoor activities, of which the most popular is always the "swimming paradise", with daredevil flumes. There are local shops and restaurants - everything you need for a home away from home. It's a holiday bubble where you can live the perfect family life that is so often unachievable in the real world.
Woburn, which only opened in June, has all those usual features, and, as befits its "city" status, has gone slightly more upmarket. The site, which cost £250m to develop, over 10 years, includes a £12m spa, massive "subtropical swimming paradise", 13 restaurants, including the chains Strada, Cafe Rouge and Starbucks and a 75-room luxury hotel. It has also introduced a cash-free system, where the same wristbands that unlock your door and padlock your swim locker can also be topped up to get the beers in.
Center Parcs, owned by US private equity giant Blackstone, has gone all out to cater to the London market. After dithering over whether to brave Friday night half-term traffic and tailbacks all round the M25, we opted for a train journey which took us smoothly up the Thameslink to Flitwick. It's a 45-minute journey from St Pancras - an everyday city commute - and Woburn lays on a shuttle bus or taxis from the station car park. Easy.
Our home for the weekend was an "executive lodge" - the second-to-top tier of accommodation with four ensuite bedrooms, modern kitchen, open-plan living, sauna and barbecue area out back, a games room with small pool table, and an Xbox if you feel the need to hire controls and play. The last time I stayed at Center Parcs - admittedly five years ago at a more standard lodge at Elveden - it was a little tired and had something of a Cell Block H feel to it, so this "executive" lifestyle, complete with daily maid service, was an unexpected treat. Only the "new style exclusive" homes, with spa pool and private car parking nearby, rather than in the offsite car parks, cost more, with an eye-watering price-tag of up to £3,500 a week.
Admittedly, none of the accommodation at Center Parcs comes cheap. Its charges have long been the scourge of Mumsnet, with holiday villages aimed unashamedly at the middle classes and above.
The exception to the "family together" ethos is the Aqua Sana spa, an adult sanctuary with infinity pool and an array of "relaxation rooms" with all the hot/cold/steamy/icy/zen/sleepy offerings a spa goer could hope for, including, of course, massages and facials. A threehour session was fun and relaxing, and I could see the "ladies' spa day out" gangs were thoroughly enjoying it.
Personally, though, I couldn't wait to get back to my favourite Center Parcs spot - the swimming pool. It's the complex's biggest draw and the reason Center Parcs won't let people in for daily trips, except to visit occupants.
In a four-day stay, we spent about eight hours there, lining up repeatedly for the Tornado, a four-person raft that shoots down the tube, dropping 45 degrees in its last stomach-churning descent.
"Don't send me down backwards," I begged the lifeguard pushing the rafts off. "Don't scream, will you?" he replied. He sent me down backwards. I screamed all the way down.
Other favourites were the Twister, a high-speed flume, the Typhoon, a fast two-man raft ride, and the Wild Water Rapids, which takes you winding out of the building and back in again, bumping into everybody else on the ride.
Apparently there are 100 activities on offer, ranging from craft work to aqua jetting, where you zoom around on underwater submersibles. We opted for the "aerial adventure" (incredible), fencing (hot and more difficult than you might think) and the falconry experience (thrilling for the children, especially when one disobedient bird wouldn't return).
And everywhere I looked, there were families on similar joint enterprises; paddling their canoe up the lake, scaling the climbing wall, steering their Segways down paths or simply riding bikes.
The sight of so many smiling faces was slightly surreal, like a real-life version of Pleasantville, the oh-soperfect 1950s sitcom in the film of the same name. Couples were chatting, not squabbling, and ruddy-faced children were rushing around, with no good reason to say "I'm bored".
Playing happy families at Center Parcs is no bargain holiday, but judging by smiles per pound, it's still excellent value.
NEED TO KNOW
A stay at the new Center Parcs Woburn Forest (03448 267 723; www.centerparcs.co.uk) costs from £249 for a four-night midweek break in a twobedroom Woodland Lodge, from £699 for a midweek break in a four-bedroom Executive Lodge, or £1299 for a four-bedroom Exclusive Lodge.
Center Parcs was founded in Holland 30 years ago. Its first UK village opened in Sherwood Forest in 1987.