You'll find the thermocouple in your ovens, they are in the flame path, the capillary from them runs up the rear of the appliance and across the top of the ovens to the gas valves on the front.
You would have to strip off the rear and top of the appliance to change these out.
Have a look at the burner in the oven and you should see the probe, very similar to the ones you have.
Is this all Belling said needed changing?
Hope this helps
I'll see if I've any diagrams for this when I go in the office in the morning. Sorry, only limited information at home.
Sorry, I don't have a service manual for this appliance and purchasing one wouldn't make sound financial sense.
Good luck with changing the parts.
Sorry I'm unable to help with this part.