insulating kitchen extension

tosker

I have a kitchen extension, built over 25 years ago, with 15cm single brick walls on three sides, which gets very cold and damp in the winter, spoiling the kitchen units and creating mould on the upper walls. My cottage is single story and very tiny, and is heated by a multi-fuel stove and leaving the doors open.

As the kitchen is only 6 ft wide, I thought external insulation to the kitchen would be the answer, but there are very few firms doing it, and those that do seem to be fully booked for ages ahead with Green Deal customers. And the fact I live in rural West Wales isn't helping, as finding a reliable builder is not easy, and I fear being sold some expensive solution by a cowboy, which has happened before.

Can anyone advise me as to possible alternatives to external insulation, which would still leave me room to move in the kitchen? COst is not the prime issue, but I do need a solution which will see me out (I'm now 68).