Er, Wattisham? I think you need to get some up-to-date FLIPs! Current LARS units are here:
http://www.ead.eurocontrol.int/eadba...2012-07-26.pdf (page 19, if the link does not take you straight to the right page).
Does this mean ALL radar equipped aerodromes with IAPs outside controlled airspace, including ALL those contained inside a MATZ, should be notified to provide LARS?
No, only those on the list linked above. Why not? Because it takes an extra controller on shift, an extra console, extra training, etc. All of which costs money. Civil units will provide it where the balance of risk says that it is a sensible thing to do and where someone is willing to pay for it. Military units provide it because it is in our interests to do so, but only at the units listed above.
When I started controlling (early 90s), there were lots more military airfields and almost the whole of the UK was covered by (mostly military)LARS. Now, not so many of those airfields are open and so more civil units provide LARS, when the cost can be justified.