Black tie event - aarrgh!

[MoveOverDarling]

Have been invited to a work event that's black tie - I have no clue what to wear, help! I'm relatively new to this job and to the industry (advertising). I suspect it's all going to be far more glamorous than what I'm used to (used to work in museums). So please dear style gurus, where do I start?

Will I need to wear a dress and heels? I never usually do, I'm more of a tomboy, tall and no hips/boobs and when I try on dresses I usually feel I look like an unsuccessful drag act. I never wear make-up either normally so would probably make a right mess of it.

Could I get away with a suit? I don't want to look mannish though. The client I am going with always looks really well turned out and glamorous!

I'm not even sure what I'm looking for, something stylish and cool I suppose that still wouldn't take me too much out of my comfort zone so I don't end up feeling self-conscious all evening...

What size/budget/colouring?

How about something like this or this with a jacket like this. Simple heels and clutch, hair up.

Thank you! Some interesting ideas. I can't wear a low cut back because of a scar. It still doesn't feel quite "me" though I realise I've given very little useful information!

Brands I like the style of are Agnes B., Margaret Howell, Oliver Spencer, Sunspel. They're all more geared towards casual elegance/sporty looks rather than a night out I suppose, but something that looks classy, elegant, clean lines and stylish...

I'm a size 12 usually though it depends on the cut. I'm 5'10" so length is often an issue. Have short hair Jean Seberg style (not quite the movie star looks, alas). I don't have a handbag, I'm really not very well equipped!

Budget - hm, I'm reluctant to spend a lot on something I'll only wear once or hardly ever, however if it were something I could dress up/down and that's more versatile I'd spend up to £250 or so. I prefer natural fibres and good quality materials as much as I can afford.

In fact, having looked through the websites I just linked I found this at Agnes B., would that be appropriate or not dressy enough for Black tie? Worn with black tights and black 20s-style heels? And some sort of jacket or maybe a shawl?

How about something like this dress

It would look great on someone so tall, top detailing would mean you don't need masses of accessories, I'm guessing you are targeting a more elegant look. It's also safe-ish in terms of flesh on show if this is the first event you've been to in your current role.

Also hiring is a great way of getting something great without having to shell out!