I'm a size 24 and would love to feel like I can hold my head high at my in-laws over Christmas. They (and the rest of the relatives) are either extremely thin or slim/average and effortlessly stylish it seems. I am so self conscious when I'm around them that I feel like a heffalump!
I rarely see them as they live abroad. So it will be a big deal and every second cousin twice removed will be there and I would love to look and feel comfortable, groomed and put together for the duration.
My normal gear is leggings/jeans and a baggy top. I don't own anything classy, can't walk in heels and at 5'10'' wouldn't want much of a heel in any case. I will have hair and nails done before we go and I barely wear make up - it's just the clothes and accessories I am clueless about.
If money is no object, have a look at Chesca - really well cut and lovely for special occasions. Their dresses are lovely, and they do lots of lovely long tunics too. Or Box2, they specialise in flowy jersey/chiffon long tops that you can wear with nice quality thick leggings. Or BeigePlus have a nice range of prices and designers. Box2 are also fab for accessories.
Have a look at Navabi. Loads of choices and good reductions at the moment. I particularly like Live Unlimited which they stock. They have nice tops that skim over the hips and look good with smart trousers.
I'm loving all of your suggestions and am clicking links and searching like a loony. How did I not know any of these places!
I think the idea of a quality dress with opaque tights and smart boots/shoes is doable. I just need to make sure it's full length sleeves or at least past the elbow as my arms are my least favourite feature.