Re FRS & small area income stats - there is quite a lot of work going on in this area and in fact CRC have funded some of it. It uses the FRS in combination with Census data to produce small-area (LSOA etc) estimates. See http://cresi.essex.ac.uk/getPubsByTag?tag=small-area for example. But of course, as with CACI data, these are model-based estimates of various kinds.

http://www.ruralcommunities.gov.uk/items/5589