I turned on the oven and the RCD tripped. When I put it on again the oven fan and light came on but it would not heat up above c.100C. The grill still works. Is it the thermostat?
NO
It is more likely to be the fan oven heating element that is around the fan you can see at the back of the oven cavity.remove the 4 screws that hold the back panel on inside the oven to expose the element.the elemet can then be removed from inside the oven cavity with care