Gopak Ltd (formerly known as P S Le Fleming Shepherd Ltd) was established in 1947, and make folding tables, folding furniture, chairs and staging in Hythe, England. Their main markets are local authorities and schools, churches, village halls and youth organisations, caterers, cafes, restaurants, venues, offices and public areas. They also sell other furniture sourced from inside and outside the UK, but much of what they sell is made in Britain. They say they are “proud to be a British manufacturer” 🙂 You’ll have to ask whether an individual item is made in Britain as country of origin is not given against individual items on their website – http://www.gopak.co.uk
Another source for folding furniture as wells as folding chairs, church chairs, church furniture, stacking chairs and classroom furniture is Alpha Furniture. Some of what they sell is made in the UK – look for items on their website that say UK made. They also sell Gopak (see above).
The CD Group of Companies, based in Derby, offer contract and domestic flooring, soft furnishing, and the design and manufacture of flooring and furnishing, with I understand curtains and soft furnishings made in-house in Derby.