A sweaty Issue!!!

Can't really think of anything except talc or some of those specialised deodrants a bit more expensive but should stop the sweating?
Actually thinking if the talc would end up going a bit funny with the sweating and maybe go on the skirt? Maybe not, hope someone else can advise you better on that x

You could employ two garters as sweatbands?

Seriously, try some decent tights (or better, stockings) with a 'cooling' finish. Some have menthol type stuff in the fabric and some are engineered to be really light, so you might be OK. I wore a pair of Jasper Conran nudes last week in the boiling sunshine and I was fine!

ETA - have just found that M&S make a pair with little bubbles of menthol that pop as you move!

I can thoroughly recommend these tights. In the summer for work I refuse to go bare legged and wear these. Even being on my feet and running around all day in heels I don't get sweaty legs or hot feet. Even in primark cheapo glossy tights I don't get any hotter than I do with bare legs.

Wow I have never heard of these menthol tights! Need some.

I can empathise with this; I sweat LOADS, but only in really specific places, ie. the small of my back (random!) and my neck. So the beautiful lacy back of my dress will no doubt be sodden by the time I get up the aisle. Nowt much to be done about that! But these menthol tights sound like a blinkin' revelation! Definitely the way to go!

Perhaps invest in some sort of cooling spray too? Not that you can squirt that up yer skirt surreptitiously!

If it's any reassurance, my personal trainer told me that fitter people sweat more. Something to do with a more efficient thermoregulation system?

*stands back and waits to be shot down in flames by science-y bods*

This is a problem i have in any skirt! but I have found that figleaves do toeless 'cooling' tights which are FANTASTIC. I will be wearing these as even in November i WILL be overheating in my dress (yeah my body sucks)

May also be good if you have open toed shoes or sandles...