One can bypass the Southend CAS as follows
Bypass 1 is 2400ft max.
Bypass 2 is 5400ft max and exposes you to a “long” water crossing which I would be slightly disinterested in doing in some rental aircraft.
But I would always be ready to fly a bypass, just in case ATC are busy.
Same with the Solent situation. You can get a transit via SAM at 4000ft but if you don’t… you have to drop down to 1900ft quick
Bypass 1 is the biggest choking point in SE England.
