i have never ridden a hub motor bike but whoosh should be able to tell you if it could get up the hills or not but even tho it folds in half it is still 20kgs
The 8-Fun BBS01 CD kit: we have two models (36V 15A BBS01and 48V 14A BBS01), chain drive electric bike conversion kit available from Woosh.
wooshbikes.co.uk
you just need a bike with the right bb im sure thy could get you one and not go to much over budget and build it for you as that will get you up the hills.
hub motors are for more flat city riding and not so good of road with all that waight in the back wheel.