What can I wear to a wedding?

[PlainVanilla]

On Saturday. South of England, in an historic building. I am flying in from abroad.
I am 5' 5", slim and 60 (short hair with no visible greys)!
Choices so far:
Silk shirt and silk trousers with pashmina
Silk shirt and velvet trousers (have 2 combinations for this)
Silk jumpsuit with jacket/cashmere cardigan thing
First 2 outfits could have thermal vests underneath if it is cold.
I do not really have any suitable dresses and unsure as to how formal the whole occasion is.

What colours are they? I’d probably avoid any black or white options.

One shirt is yellow and matches the yellow (more like old gold) in the trousers. One shirt is a steel blue, the other is navy with cream spots, velvet trousers navy. Pashmina, jacket and cardigan all navy, jumpsuit navy with tiny white or cream lines in a pattern, but looks navy and was worn to a wedding in the summer (at which at least 50% of Saturday's guests will have been present).
I don't wear either black or white ever.