What kind of top? Help needed.

I have no idea what people are wearing these days for the same reason as you! Have you thought about hiring an outfit?

I might be way off what you like here, but if my husband were wearing a formal dinner suit, I would try to match him with a blouse with some kind of detail like a bow or pleating. I'd cover up as much as possible, but sheer sleeves are nice.
I'd start with black, some examples here are Reiss, Next and I can't remember what. If that is too dark, then I'd move on to maybe cream or nude. Either way, a good camisole is de rigueur. You can add fine jewellery to dress it up. Have a great evening.

Sorry, my phone is rejecting two of the images at the moment.

Personally, I love a tuxedo suit - I would be lost without mine.

Have a look at Zara. They have beautiful evening tops, and as you are only a size 10 Zara's clothing ought to fit you.

I'd either hire a lovely long dress or find a gorgeous long sleeved top in a colour that really suits you with which you can wear a beautiful piece of jewellery. I'd wear the top with black trousers in a beautiful fabric like velvet or satin but if you want to wear your skirt, just make sure it balances with the top. Have a lovely evening and once you have got dressed forget about the clothes you are wearing but wear a smile!

What a lovely invitation to have!

I would probably opt for a dress from Hobbs or Phase Eight or for a slightly more affordable option a cream top would look great with a black skirt.

Mint Velvet or Next would have a nice selection.

Roman have a fantastic sale, dresses are as little as £30.
Here’s an example.

Buy a new dress from somewhere like Zara, in a colour that suits you. A cream lacy top or dressy one, accessories make an outfit, beg or buy a nice bag, with one statement piece if Jewell’s, nice earrings or necklace. Most of all enjoy yourselves.

This looks good, and, you could wear all 3 parts separately after the event.
I would add a chunky necklace with it

I'd probably go and buy a long dress rather than faff around with trying to find a matching blouse. At least you'll know you will "fit in". Hope you have a lovely evening.

If be inclined to wear soft black trousers with a black top. If you can wear black next to your face. Break it up with jewellery. Bangles perhaps.
You could lift it all
with a beautiful coloured wrap or pashmina. Nothing needs to be expensive. Try Klass. Shops or on line.
An evening bag.
Would any friends have anything suitable you could borrow?

You haven't given your height . I think that it can make a difference .
As you are so slim -that's a huge advantage .
I wouldn't wear a short skirt to a black tie dinner . I'm not sure about a glittery blouse .
Can you photograph them ?
Hiring is a very good idea .
I usually rely on Monsoon for most occasions . I know that I'm going to get a lot of wear out of their dresses .
Enjoy your evening .

I buy evening dresses from charity shops or eBay. They've often only been worn once and only cost a few pounds, probably cheaper than a new top.
Wide leg trousers and an oversized blouse ,tucked in, is the fashion at the moment.

Long black skirt cream lace top preferably one that fits just over the skirt waist band.
Dont try to look younger than you are.
We older women have elegance on our side.

A full length dress or cocktail dress, importantly in a colour that suits you would be ideal.
Only wear black if it suits you as it isn’t necessary for a black tie event.
Have fun!

Silly of me not to give my height because at just under 5ft short I find trousers don't do anything for me (although I wear them every day at home). I have to take care not to look 'girly' and I'll never be elegant.
When we were young we used to go dancing and I had long dresses and skirts, all since gone to charity shops. We are very unlikely to go to anything as smart as this again, hence my not wanting to spend much.

ExDancer - maybe trousers would look wrong as you are petite .
Fine to wear them at home as I do most of the time !
I'm wondering what my petite friends would wear to a black tie dinner .
If you don't want your spend a great deal -have a look at ebay .
I always think that tiny sizes have the best bargains .
I always deeply regret throwing any clothes out .
Now I've been invited to an Afghani party - I need my shalwar kameez or maybe a caftan .
Fortunately , Monsoon usually sell
caftans , but unless on sale they aren't reasonable in price .
I might go to Brick Lane in London to see what's available .
Failing that , ebay .
I might be able to get a blouse and lengha and that would be beautiful .

This is the best I can do with a photo. I felt the top was a bit too Christmassy - and a new blouse would be wearable at other times.
I can't afford something I'll only wear once.

Thanks for all the suggestions.
Esmay what's a lengha?

I’d go for a long or midi dress , rather than faffing about with skirts and trousers and the right tops . Next do a petite range. Maybe find one with 3/4 length sleeves .

I love the skirt and the blouse but I wouldn’t put them together as each cancels out the design of the other. I would either buy a plain black skirt, velvet if possible, to wear with the blouse or buy a black or gold top to wear with the skirt. Each garment is lovely but, personally, I wouldn’t put them together. I particularly like the skirt - that’s what I would choose to base my outfit on.

IMO this skirt would look better with the top.
And is on sale, and, it’s in your size 😀

ExDancer -
A lengha is a Indian /Pakistani wedding or party skirt worn with a short or long sleeved saree blouse .
It's A line and has lavish embroidery especially on the hem . The waist is usually tied .
They are often in wonderful colours .
I love sarees , shalwaz kameez , but lenghas are my absolute favourite item to wear .

Thank you for the photograph .
The top is pretty and so is the skirt .
I feel that the top slightly overwhelms the skirt .
I'd be inclined to change the skirt for a longer one or to change the top for something less glittery .
It's your evening and if you're happy with your existing outfit , wear it and enjoy it remembering that every other woman there has agonised over her outfit !