We recently had underfloor insulation installed by Barry Sapwell, and can't recommend him highly enough!
We live in a Victorian conversion with a mix of exposed wooden floors and carpets and have had the heating pumping all winter to keep the house warm against the drafty floors.
Barry installs insulation underneath the floorboards in Victorian houses, still allowing the air to circulate underneath the house, but keeping the rooms a lot warmer - we actually had to turn our heating down the first night after it was finished! He lifts as few floorboards as possible to minimise mess and prevent damaging the boards.
Very reasonably priced, we're expecting to see a big decrease in our heating bills as well as having a much warmer home!