Many of the new superfabrics are appropriate, as well as traditional Loden, and moleskin. Care with Gore-tex, as in it's simplest form can be very noisy, Goretex lined clothing is probably a better choice. Similarly, keep away from the traditional waxed jackets for stalking, again the noise is likely to ruin a near successful stalk. Whilst on the subject, a good pair of gloves is useful to cover white hands in the Summer, and essential to keep feeling in your fingers in winter. Woodland stalking presents little need for extensive hiking, so one has a bit more latitude than hill stalkers in the North.
Many stalkers feel lightweight wellingtons fit the bill.
Part of the charm of Driven bird shooting in the UK is the etiquette and tradition that surround it. A Driven bird day is a relatively formal event, and a smart clothing code operates. This varies in degree from estate to estate. This however is less common now, and as long as a few basic rules are followed, you need not feel out of place, or spend a fortune. Ask your host before the day to ensure that you aren't over or underdressed.