Jubilee party clothing- please help me not look a tit.

[waitingtobeamummy]

A group of us are organising a jubilee party (daytime to evening). We have agreed its a fancy dress or red/white/blue. I thought it would be easy to get something un-naff as I have a perfect idea in my head but I can't find anything!
I was thinking vintagey/retro tshirt with something jubilee-ish on it maybe the queens head, a corgi....."I love london" (but not touristy). I have seen a lovely cardigan in asda with little crowns on it and then maybe jeans? And then lots of pearls but somethig for my head?
I loved the cath Kidston jubilee tshirt but I cant afford it and I'm worried it won't stretch over my boobies
I am a size 16/18 on top and 18 on bottom half.
Oh and we will be outside in the evening so I need something warm.
Humour me and help me please?

Go really retro/vintage: a Sex Pistols "God Save the Queen" T-shirt and punk bondage trousers. Mohican and safety pins optional!

Navy shirt dress, bright red lippy, white court shoes, retro hair style?

I'd probably go for a deep coral & mid blue combination that I could wear again. E.g jeans/narrow chinos in blue
Top combining coral/white & maybe blue with a coral cardi over. I'd then go to town on shoes like something from irregular choice.

primark have t-shirts with a corgi on or crowns and one with the queen on i think if you have one near by pop in they were in red or white and around £5
hth

Asda are selling long strings of red, white and blue beads, if that helps.

Thanks All!!
I got my lovely cardigan from asda, I think the deep coral idea is lovely. I have recently lost lots of weight, and have forgotten I ca wear things other than jeans or black trousers so I am going to get some dark blue chinos. And I will have a look at the primark tshirts- I am going in a couple of weeks time. Thank you all lots for your help-btw our neighbour is a punk, whole sex pistol safety pins job, so I dont think I will go for it haha!
Thanks again!