If i were you i'd look at a marshalltown pre-worn permashape trowel at around 30 quid, as there pre worn you will find it easier to use for a novice and get better results as the blades slightly curved and bevelled resulting in less trowels marks .
For both you're looking at 2 and half tonne of ballast and around 22 bags of cement which means alot of mixing not sure what the materials would cost you, if i was doing it and the access was ok i would get barrow mix 2 cubic metres.
how bigs the area? if its only a couple of feet square and you've only got bonding i'd use that, i have before now but if you're doing full boards get adhessive