This is heretical territory, but if there's one tale that's been repeated time after time by those out on the election trail, from every party, it's that what they find on the doorstep doesn't reflect the opinion polls. Even Jackie Ashley in the Guardian gave a coded warning that things could be much worse for Labour than the polls suggested. The polls, I think, have failed to capture the national mood of anti-politics, and perhaps anything could happen on Thursday. Your guess is no better or worse informed than the foremost TV pundits.
And remember how wrong the polls were in 1992; out of 50 published polls during the election period, 39 predicted a vote share that would have resulted in a hung Parliament, eight suggested an outright Labour win and only three predicted a Conservative majority.