My criterion for "likely Labour seat" are the "red" seats on Electoral Calculus, which seem to be equivalent to around a 15+% majority for Labour:
www.electoralcalculus.co.uk
The "pink" seats are very optimistic Labour gains and likely to be Con holds, but anything with 15+% majority I think will be a Labour gain.
This still means, for example, Labour winning both Bournemouth seats and the entire Red Wall becoming red again, but places like Wokingham and rural parts of Northern England are I think a pipe-dream.
Echoing comments about Hartlepool, supposedly the poster-child of Johnson conservatism, the predicted result isn't even close for the Tories.