Can oven and hob be wired into oven socket behind the oven

Depends on a lot of things. My advice would be to get an electrician round to advise/ quote you

As long as there is a dedicated cooker circuit going back to your consumer unit, there should be no problem in doing this. As always, if you are not sure - consult an electrician. SPH Team

Yes. But depends of the total power of that circuit (cooker and oven combined). A 32 amps mcb protects up to 15kW with a 6 /2.5 mm cable arrangement. Today, most appliances needs to locate the switch isolator in a accessible position and properly identified. Also from a convenient distance from the hob. Call an competent electrician, who were able to do an electrical calculation to determine if it is safe to do so. Best Luck.