Essentially, there was no plan, he was hoofing it, and I was naive enough to trust him. Decided against letting him have another crack at it and instead will look to level it all out and then using paving bricks the same as what's already down. Looks easier at least.
Block paving arguably takes more prep and will be a bit more difficult to get to the same height as your existing paving. You have to allow for the compaction of the sand bed under the blocks after whacking them.
Slabs should be easier, you can just add or remove mortar to achieve the desired height.
pavingexpert.com is the go-to resource for anything paving related.