It's as inevitable as Heston pud sell-outs and Auntie Barbara getting carried away with the Sherry... the Christmas party countdown has begun - cue a bombardment of '5 weeks to party dress perfection' diet plans.

[Read more: Why do we pull crackers at Christmas? The story of a great British tradition]

1. Ditch the diet

There's nothing wrong with wanting to look your best and maintain a healthy weight. But there's a lot wrong with falling into the 'diet' trap and thinking a special occasion means you need to starve.

"Diets are a false economy. It's not just Christmas - it's year-round, a wedding comes up, a holiday comes up. Crash diets, detoxes, shakes for two weeks, all a false economy," says Kevin Foster-Wiltshire, Reebok UK master trainer and creator of leading online fitness community GymCube.

"Too many people are fixated on the number on the scales, but it's about how you feel, how your clothes feel."

"It really is about finding the foods that work for you, that make you feel your best - and then you'll want to make it a lifestyle - and having some sort of 80/20 rule [being 'good' 80% of the time and 'naughty' 20% of the time]," adds Foster-Wiltshire. If you really do want to streamline for your party frock, he suggests sticking to balanced eating habits but switching from 80/20 to 90/10 for a while and paying close attention to water intake.

2. Make up for it

Too timid to try a statement lip, or an edgy eye? You might be amazed at the transformative power of experimenting with your make-up, and being a little bolder than usual.

"It's easy to get stuck in a make-up rut, but the festive season is the perfect time to switch it up and try something new," says Press Association fashion and beauty editor Katie Wright. "My top tips? Matte lips are the trend of the season, so try a red velvet liquid lipstick, which feels like a gloss but dries to a gorgeous shine-free finish.

“Glitter is having a catwalk moment too - what could be more festive than a sprinkling of gold sparkle on your eyelids?

“And if you want to carve yourself some killer cheekbones without resorting to surgery, then cream highlighter is a must. Dot the shimmering liquid along the tops of your cheekbones, blend well and you'll be party-perfect."

[Read more: Why Christmas dinner is good for your skin]

3. Body talk

If walking into a crowded party makes you a little anxious, the old adage, 'Fake it 'til you make it', really can work wonders, especially when it comes to body language.

"Uncross your arms. Nothing sends more negative vibes than having crossed arms; a defensive pose," says life coach Olga Levancuka, author of Increase Your Confidence In A Day.

"To help yourself feel more confident, get a glass of water. You'll feel a bit more relaxed holding onto something.

“Give people time to relax and pull yourself together by imagining you're the greatest speaker there is and the people are your audience, eager to hear your speech.

“That'll help your body look straighter and taller, hence you'll be more noticeable, and someone's bound to come over and strike up a conversation."

4. Mirror, mirror

What do you mean you avoid full-length mirrors? It's time to get acquainted.

Now give yourself a little positive pep talk. If that doesn't come naturally (it takes practise) then simply talk to yourself as you would to a best friend.

Get comfortable with your body and show it some love. And hopefully, whenever a big party rolls round, you won't feel that nagging urge to 'change' it in order to enjoy yourself.

"One of the best ways to improve your body-image is by using positive affirmations in the mirror. By beginning your day speaking kindly to yourself, you help rewire your brain to focus on the positive aspects of yourself, and it'll make you less likely to focus on your flaws and imperfections," says body confidence expert Michelle Elman.

5. Resolution revamp

For most of us, doing more exercise is routinely top of the New Year resolutions list. But why wait?

Take the pressure off, and start now - just for the joy of it.

Those endorphins come in very handy with these pitch-black evenings, and again, when those parties roll round, feeling content with yourself will just be second nature.

It doesn't have to be hardcore, and not having time really doesn't fly - use online workout videos if you can't get out of the house and it literally can just be a case of 20 minutes, job done.

How do you feel Christmas party ready? Let us know in the Comments section below.