Hi there,
My Beko C4 also failed with the same problem as you (failed on February 12th). Lights would come on, but grill/oven don't heat up. Hobs work fine.
Turns out a wire had burnt through. If you disconnect the power and remove the back, there is a connector block near the base and you may be able to spot and replace the broken/burnt wire. You'll need to use the correct guage of wire and the engineer may have used some crimp spade terminals, rather than just screwing the wire to the block.
Jon, February 2009