its not as mad as you think for this particular area… Forestry Commission do share the forest between civvies and the MOD. Rendlesham Forest (quite near me) for instance has a barracks and a (disused) aerodrome just nearby.
I’ve got a copy of a load of pages from this book written by the grandson of Lord Tennyson (who wrote the poems) about Suffolk. Halfway through it he mentions being in the exact bit of Thetford Forest where we used to have a lot of raves. he mentions being able to see the (then new) A137 from inside the forest, but not hear 3 large trucks going past (he could see them). This was in the late 1930s when they didn’t have any of the new silencers or quieter engines of today, so you can imagine the racket a large truck would normally make.
they do hold events in the forests, some mainstream pop concerts and in Rendlesham they do open air theatre – its just that no one from the dance music scene has got it together enough to sort out a licensed one or hold a unlicensed one without annoying the neighbours or leaving too much rubbish behind.