Another recommendation for Alex at Crown Joinery - he swapped a rotting, drafty back door on our kitchen extension with a chunky, hardwood, double glazed, draft-proofed replacement and a matching window. When he came round to fit it, he had a nightmare - the previous door seemed to have been installed in little more than cardboard, but he worked solidly for two days, found an emergency bricklayer and did a fantastic job. A double-glazed hardwood door isn't cheap (c. ?1200 supplied and fitted), but it has made the kitchen much warmer already.