If you mean the large 9 sided zone covering most of London Zone 2 - then there’s a whole thread about it:
The conclusion is that you can fly there - the restriction only applies to helicopters.
Obviously within that area are no fly zones (eg central London, the heliport etc)
Red zones cant be unlocked
Not sure what you mean - there are plenty of areas marked as red zones on the map that are fine to fly in. For instance the huge London CTR. It’s a red zone but the restriction is just class D - ie not relevant to normal drone flights.