As time goes on we'll know from other countries' experiences how far we can open up the UK. We have the advantage of being a couple of weeks behind most European countries and can learn from their actions.
On an optimistic note, it's possible that stadiums could open to spectators again this year: maybe with compulsory mask-wearing and alternate seats (and possibly rows) left empty. With strong warnings for anyone particularly vulnerable to stay away, and anyone with symptoms likewise. It would be a bit limiting for those who like to shout support (or abuse) from the stands, but that's a small price to pay for live football with a bit of atmosphere.
Yes, the virus may spread again to some extent, but with these measures, general social distancing, and a better understanding of how it spreads, it may be a reasonable compromise. We have to accept that we can't get rid of it entirely without a vaccination programme, and also that we can't stay in lockdown for months more - that would take an increasing toll on those who haven't even contracted the virus. Lockdown isn't a safe place, it can only be a temporary measure to prevent the NHS being overwhelmed with serious cases.