May will likely win a landslide.  Labour Party might get above 30%, but even that will be an uphill battle, but with the Tories pretty much swallowing up all the UKIP votes from last time, that means they are in the high 40s rather than high 30s so pretty much any riding where the Conservatives + UKIP got more votes last time can be expected to flip in their favour.  If the party was smart they would dump Corbyn and try and get a more moderate leader.  The London mayor Sadiq Khan would be the one who I think they should choose.