Danny, I would forget about purchasing the electronics until you have a design sorted out, budget for them but don't actually purchase them. Not always best to buy a kit either, doubt there is anything wrong with the kit you linked to but the power supply is only 36v so you have already limited both your drivers & your motors, there are some useful sticky posts that help explain some of this if you have a look through the forum.
METAL & WOOD WORKING - FAQ's, Problems & Solutions

Have a look through the sticky posts as some of the things you need to know are covered.