Help needed for flabby arms cover up!

[oneburgerofham]

I am going to a wedding in September and am looking for a shrug/cardigan/whatever to wear over this Monsoon dress. I am a size 20 so am a little limited for choice, could pay up to about £40.
Any help very gratefully received!

[Botanicbaby]

I usually cover up my arms with a nice silk pashmina, would that be an option?

I've also got some fitted sparkly bolero type cardis from Monsoon that do the job.