It's not just halls. It will be impossible for lectures to take place in Universities come the autumn with, as Chris Whitty said earlier, "highly disruptive" social distancing measures in place. As a current University student, I can say that University lecture theatres are packed full, with Universities trying to recruit as many students as possible to boost their tuition fee income. Ok, the autumn 2021 first year intake might be down, but current year groups will still be there.
It will be impossible to have all students in a lecture at least 2 metres apart. I can see all University lectures being online until at least the Spring term 2021. Same for University libraries. My Uni library is usually packed, no way can students be kept 2 metres apart without drastically reducing capacity, like having 1 or 2 students around a table instead of 4.
And this is all before even thinking about what many students go to University for, the socialising in pubs, bars and nightclubs, which surely will be impossible under strict social distancing rules.