What to wear to a 40th party

[pisspants]

hi all. I have been invited to a big 40th birthday party which will be about 100 people, disco in a happy type thing. There will be a mix of people and ages there but mostly around 40ish years old. I am going in a group and not with anyone I know really well so I want to look good enough to be comfortable in myself but not be too "out there "
I am not very stylish and am short (5'3") and a size 14 to 16 with big boobs. I have to be really careful what I wear so as not be either wopping them out or looking matronly!
I dont have a lot of money but could maybe spend up to about £50 or £60 on a new outfit. Ideally something I would be able to then use for work or to wear at the weekend in the future.
Because of my shape I prefer to be able to try stuff on rather than order online as I have had more online disasters than successes but I have access to most high street shops nearish by.
So I was wondering if anyone has any ideas on what I could wear as I am hopeless and I would be ever so grateful x

bumping as am truly hopeless and in need of some advice!!! thanks people

Have you got jeans/shoes? Might be easier to find a top to go with those than a dress?

I'm 43 size 12-14 with G cup boobs but good legs & same height as you, so for a party I would wear dresses that are shorter as I find midi swamps me!
I like River Island, Oasis, Lipsy at Next, Zara etc
I don't buy bodycon as I have a tummy I like dresses that either skim my shape & have ruching for example on the tummy area.

I would also recommend skinny black jeans IF they are not faded or black trousers with a pretty top.

Then you just need a pair of heels & a nice bag plus suitable jewellery!

Also Wallis can have some decent options.

Wrap dresses can be flattering for the generous of boob - what about:

www.asos.com/yas-petite/yas-petite-auho-puff-sleeve-wrap-dress/prd/13261316?clr=&colourWayId=16473707&SearchQuery=midi%20wrap%20dress%20petite

Or

www.boden.co.uk/en-gb/alberta-jersey-dress-forest-polka-dot/sty-j0602-pgr?cat=C1_S2_G4&pid=J0602-J0602-G_00000002663

Or I agree skinny black jeans make a great base - if you want to keep it really simple something like this?
www.debenhams.com/webapp/wcs/stores/servlet/prod_10701_10001_36194+098975001_-1

thank you people! I really like that Wallis top and think I will go for skinny black Jean's with a top with heels as I think I'd feel more comfortable in that rather than in a dress and would get more wear out of the items.
I think I'd probably need a size 16 top and they have sold out but will keep looking for a nice dressy sequinny top