You must be all dreaming...
UK Gov. is never going to fork out for any of this. Wake up! Cant even afford and pay for a maritime patrol aircraft, let alone a ....what exactly? Which is looking for what...against whom?
By 2030 you'll be lucky if you have a handful of airbases (2 or 3 including Scotland if) with some Eurofighter, ground radar and a few MPGS.
A new Sentry is not high on any UK Govt. priority.