Mat,
Hi,and welcome to the forum.
This has been covered in a similar post - click here
http://www.kitchensfitted.co.uk/KitchenForum/viewtopic.php?f=1&t=99and it really is dependant on the output of your oven.
Generally, single ovens can be plugged in to a switched socket on the supply providing the existing circuit is capable - e.g. a ring circuit or an allowed spur outlet taken from the ring circuit.
In your case however, you are also fitting an electric hob and this will require it's own dedicated supply fed from a Cooker isolation switch.
If you already have a dedicated supply then this can acommodate both appliances "hardwired" as you put it.
If there is none existing then I'm afraid you will have to arrange installation of a new circuit back to the fuse box.
It's imporatant also to remember that all electrical work on your house supply, must be carried out by in compliance with Part P regulations and must be undertaken by an approved operative.
Tim