Thanks Chris. A bit beyond my DIY skills I am afraid but I am happy to
pay for the professionals to do it if not too expensice. I see there
are grants if you use solid fuel central heating (or solar or
heatpump), but I was always concerned that solid fuel required a lot of
manual intervention (cleaning it out - refilling etc) as well as the
unknown factor of running costs......

Perhaps I should look into this a little more.

Cheers
Fly