Have a look at some of the Driven Boar videos, take no notice of the shooting, the blank bits and waiting time has been cut out !
Have a look at the clothing as the guys walk into position.
You will see allsorts of jackets and trousers, very rarely a suit and even more rarely breeches, in fact I only know one or two that wear breaches and they aren't the normal 'pig shooter' they posed more of a fashion statement !!
I wear green/brown Deer Hunter high back Montana trousers or Harkila gortex, sometimes I wear a tweed jacket or a Jhakti Jahct jacket, The jacket isn't that important as long as it keeps you warm as you may have to wear a hi viz vest or arm bands.
It is also very important to make sure you have some decent footwear, either ankle boots with gaiters or high boots. I would not suggest wellies unless high quality as they will make you sweat and when required to sit in a high seat/house you will freeze your tootsies off.