There are two independent sources of data on actual numbers of mortgage possessions: The Council of Mortgage Lenders (CML) and the Financial Services Authority (FSA). However neither source has data on the number of bedrooms of the property being repossessed.
The Council of Mortgage Lenders latest press release on repossessions is on their website at:
http://www.cml.org.uk/cml/media/press/2262
The Financial Services Authority data are available on their website at:
http://www.fsa.gov.uk/pages/Doing/Regulated/Returns/IRRystatistics/