The functional reality is
"Spare" council and social housing have been rare as hen's teeth back since at 2015 least and whatever little is available is awarded based on a priority scoring system - the obvious priorities being women with young children, pregnant women, people with significant MH needs, people escaping violence or unsafe conditions.
He's male, under 30 and OP has not mentioned anything about vulnerabilities / at risk of /needing to escape violence
What happens next is he approaches his local authority, he fills in forms, they assign a priority score for him and terms of accessing long-term social housing, he ends up so far down the list he's wasting his time
The best the council are likely to offer a single young man without dependents is temporary accommodation (Local Authority-contracted bnbs, bedsits)
and he'll only be offered that "help" if he stays in his present accommodation until formal eviction proceedings reach the threatening letters and bailiffs stage, if he chooses otherwise, the LA will deem him intentionally homeless and they get to discharge their responsibilities towards him.
In 2017, Shelter found loss of tenancy one of the key routes to homeless and in 2017, the rental market was becoming quite wonky in terms of availability, but compared to present day - hugely plentiful.
He will be entitled to Local Housing Allowance. LHA is very rarely anything approaching the full amount, its usually around 50% give or take - this varies by area/region. An LA can (or used to be able to), make a discretionary payment covering the first 6 or 12 weeks at full rent