Stylish afternoon tea and a photoshoot, pls help!

[coffeenut]

I have a posh afternoon tea party to go to for an elderly relative of DH. It will be a huge event with extended family and as I understand it there will be a photographer there. I'm really stuck for what to wear.

I should add it will be warm-hot (where I am) when this is scheduled. Normally for photo shoots I'd go neutrals, blues etc but I need something "pretty" and fashionable enough for this sort of thing and also something flattering (DH's family are very stylish & slim ...sigh). I hate my thighs and my arms to my elbows ... does anyone have any ideas??

(I should add that I'm a size 10, 5'5, but I have the tendency to look matronly in anything unstructured).

Silk blouse pencil skirt and heels?

silk blouse with sleeves plus a tight pencil skirt may be too much if it gets hot. I wouldn't do a sleeveless if I was going to be photos as my arms always look extra heavy IYKWIM?

It is definitely a fall-back option that i've considered though, thanks Clackety. I have an Oasis blouse with 1/2 sleeves that i might be able to get away with but it is black.... argh. Maybe if I put it with a pretty skirt?

I do have a cobalt blue jersey Baukjen dress with elbow length sleeves ... not sure if this is right for the occasion though.