Probably just a bastard thick cable into screw terminals on the hob. Required tools are likely to be an assortment of screwdrivers, but probably wise to have wire cutters/strippers on hand too. Part P shouldn't be an issue due to like-for-like appliance replacement.
If the cable needs replacing due to being too short, then you'll probably have to go back to the Big Red Isolator Switch™ (I wouldn't introduce an extra junction on a high-current circuit unless I *really* had to). Again, screw terminals, and anything you need to do sort out the physical arrangement of the cable (plastering, conduit, etc). Obviously it needs to be the same thickness of cable.
Note the importance of screw terminals being done up bastard tight: If they're loose, the junction's excessive resistance leads to heating, which loosens the screw, which increases the junction's resistance, and eventually either there's a funny fishy smell and your cooker stops working, or worse.