The normal way is to use a double cooker connection unit so you can have two separate supplies.
The rules allow one to have a trip at the destination if no more than 3 meters of cable and unlikely to be damaged, however there is normally no fuse within the units so in theory should have cable able to take current of the trip in the consumer unit, however it is unlikely you can get the 4 or 6 mm cable into the terminals of an oven, and oven not normally over 20 amp so although not strictly within regulations, I think most will use 2.5 mm cable.
The hob however may go over 20 amp, so you need to read the spec for the hob, I note my mothers old hob said 32 amp supply so that would need at least 4 mm cable and normally thermal setting cable is used not thermal plastic (90 degs C not 70 degs C) also when changing you need to comply with current regulations, so if a RCD is not fitted it will need an RCD fitting.
It is possible if there is free ventilation that you may get away with under sized cable, or that a special cable is fitted able to stand a higher heat, but normally we consider 2.5 mm good for 25 amp max, so read the book which should come with the hob.
The cooker itself came prewired with a 2.5mm cable. the induction hob came and specified a 2.5mm cable to be used also.
The unit would be less than 3 metre cable on it from the fuse/cooker+hob. This is currently a 6mm cable to the Cooker switch and then 6mm cable into a block terminal. My thought was would it be sufficient to wire into this block with the cable from the hob and the cable from the cooker.
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