DECC publishes quarterly updates on the number of homes in Great Britain with loft, cavity and solid wall insulation. These estimates are based on a variety of sources and are published as Experimental Statistics.
There are 26.7m homes in Great Britain. 
It is estimated that at the start of April 2012, of these 23.4m have lofts, 19.0 million have cavity walls with the remaining 7.8 having solid walls.
Through government schemes since April 2008 (the start of CERT), there have been 4.3m lofts, 2.2m cavity walls and 64,000 solid walls insulated.
Compared with January 2012, 500,000 more properties had loft insulation, 280,000 more had cavity wall insulation and 6,000 more had solid wall insulation.
14.6m homes had loft insulation of at least 125mm (62% of homes with lofts). 11.5m homes had cavity wall insulation (60% of homes with cavity walls) and 129,000 homes had solid wall insulation (2% of homes with solid walls).
If you are a householder and you don’t have insulation or only have the minimum amount, you should seriously consider have it looked at and remedied by experts. It makes sense and will save on energy running costs.
More information: www.decc.gov.uk