Register with the
UK AIS and you can get free access to the Civil AIP (En Route Sect 5) which will tell you all about the danger areas, restricted areas etc. Southern MDA is a mil training area and is activated as required. Base level is FL50 so you could go below - or you would have to get a service from, I guess, London Mil or Civ.
The others sound foreign - I guess you would have to find their AIPs.