here's a quick What Is To Be Done? for the UK left, from a humble twitter squirrel: stay in labour or join it if you haven't already to ensure that the left keeps control of the party leadership. even if you can't actively organize for it, just being a member gives you a vote
there's going to be an alt-centrist onslaught against the left now as they try to recapture the party and turn it into a neoliberal PR machine once more, and shift its policies to be "racism + whatever Murdoch wants". that has to be stopped at all cost
be prepared for a barrage of immigrant and muslim bashing. of course, this is the kind of racism that the media and pundit class, the core constituency of alt-centrists, absolutely love and will help boost, namely actual racism rather than a fabricated smear campaign 
objective conditions for an election now were bad, particularly two key factors: 1) the economy, though bad, is not at crisis-point like in 2007/8, which brought Obama to office, and 2) brexit swamped everything else. by 2025 brexit is gone, and an economic crisis is likely
if alt-centrists are able to take over the party and, solely due to these objective factors win the next general election on a tory platform, *that* will be the death of socialism for a generation. same goes for the US if biden gets the nom and beats trump
the situation is in flux at the moment, I don't know whether the labour left is powerful enough to hold onto the leadership. cowards and play-pretend "leftists" like paul mason have already caved and are openly advocating for an alt-centrist "compromise" candidate. it's bullshit
what'll likely happen is his ilk will prop up a owen smith/mayor pete/warren type candidate: use left rhetoric and pretend to support left policies to fool the membership, then, once secure in their position, abandon it all and show their true colors. don't fall for it
one thing is for sure. the internal battle that's going to be waged over the next months is going to be very tedious and annoying. the media and other power centers will throw everything they got at it. if this is too much for you to handle, it's alright to take a break from it
just make sure you stay a labour member or join to become a member so you can use your vote when it matters. there's already a campaign going on by alt-centrists to play up disillusionment among the left and try to get us to leave. don't give those scumfucks what they want
these are the people chiefly responsible for what happened, with their deranged remainiac fantasies. some of them are even talking about how we need a leader who will campaign on re-joining the eu. they're absolutely delusional, and need to be utterly destroyed. make them cry
and remember: alt-centrists lost miserably in 1987 (kinnock, leader then, even stayed on after this), 1992, 2010 and 2015. yet despite this miserable track record the media doesn't advance a "alt-centrism is electoral disaster" narrative because they're alt-centrists, too.
a couple of things to remind yourself of to ward off understandable feelings of disillusionment (which, again, is being actively encouraged by alt-centrists): Gramsci's "pessimism of the intellect, optimism of the will", and these wise lessons from Gould, Marx and Brecht
here's the tl;dr version
