Its difficult to see how Labour can win enough seats off of the tories for the tories to lose the election. Most marginal tory seats had a significant UKIP vote in 2015 that should act as a buffer for them. Labour certainly havent targeted UKIP voters. Labour seem to have been targeting its own safe seats rather than tory marginals eg they've been chasing the student vote, most of whom live in safe labour seats. Their campaigning seems to have been focused on safe labour seats. The polls are predicting that the tories will increase their share of the vote, albeit by less than labour. But increased vote share doesnt usually lead to lost seats. And the tories are predicted to pick up a few seats in Scotland.
I expect Labour will significantly increase its share of the vote, significantly increase its majorities in the seats it holds, but not win many new seats.