All my savings are in ISAs and not paying tax in the UK (nor in Belgium actually, due to the scheme I'm on to encourage overseas scientists to come here). So nope, you get nothing from me (actually I still pull out as I have lifetime ISAs )
Pret? Behave, that's like playing Russian Roulette.
As for your other points, if it's not sustainable, do you still believe bankrupting the country just so you can continue as we were? After all the biggest draw on our taxes are the elderly - they're the biggest users of the NHS, and the pension is the majority of the welfare budget.
Personally I'm all for reducing immigration as long as we reduce the current state pension, and privatize the NHS.