I think if anyone suggested that this lockdown will continue until Sept/October there would be riots. Half a day at a time. I keep imagining how long the queues on the M1 might be when every one heads off on the same day 
I agree - it's going to have to be a long time but to suggest that might cause people to go bonkers and think what the hell, and drive off to holidays spots anyway!
There can never be a predicted
date that restrictions will be lifted because of the unpredictability of the epidemiology of this virus and especially in realtion to the measures taken to restrict its spread.
It might be possible to suggest a
stage at which we can think about easing restrictions. For example in Wuhan which was so severely locked down, resctrctions were only eased after day(s?) where
no new CV-19 deaths were reported. Since our numbers just in hopsitals were almost 1K yesterday, it's going to be a long time before we return to that situation in UK.
Might be a while before we can go on hols though I'm still hoping for our late July one in UK...
Hurdity x