Need clothes for a conference I am running!

[atriskacademic]

I am university staff and am running a two day conference mid June. Needless to say, I will be on my legs all day, organising everything and at some point presenting myself (on both days).
I just realised I don't have any clothes for this. My normal work wear is black trousers and loose mid length shirts (I mostly buy from Roman as they do loose fitting things). However, I feel another heatwave potentially brewing mid June, so I urgently need T-shirts and trousers that mean I am not sweating myself to death.
I am 5.4 and overweight. Normally wear size 20 trousers and size 18 tops. Everything needs to have stretch, otherwise it won't work for me. Like trousers that go high up. Hate hate hate shirts with slits on the side, unless the shirt is really wide. HELP!
Also need to add - dress code in my field is not terribly formal. Smart casual essentially!

How about loose, floaty wide leg black trousers? I’ve found Airism Uniqlo tops to be great on hot weather - they come in a few colours and I’m a similar size to you and find that XL size gives me plenty of room.

Thanks! Will have a look at the tops. I always find Uniqlo fitting relly small on me. Generally don't like wide leg as it makes me look even more like a barrel...

I’ve felt the same about Uniqlo but the loose fitting ones I found recently were much better.