Since I wrote the original post I discovered the UKATZ and UKMATZ scenery programme.  I loaded this into FSX with the correct pointers and ran the Navigation Database build prog and now all the MATZ zones are showing on the map although some of the "military" fileds are shown with a black bar which seems to indicate "civilian" fields.

I don't seem to be able to see MATZ airfields when looking at the map.  They are supposed to show with a darkish blue boundary but I can't make them appear.  This means that some military airfields (eg Yeovilton, Boscombe Down, Odiham) not only appear as civilian airfields but also have no MATZ zone markings.  It is also very noticeable in Lincolnshire/Yorkshire where there are many military airfields.  Is this a problem with my settings or with the program itself. Otherwise I think it is great and I can use it with FSX and VoxATC, brilliant.