Is the clock flashing?
Ok so the time is set when you turn the dial to select a setting does the little red light on the front come on?
Ok what this may be is a burnt selector switch. As I used to replace quite a lot of these as they burnt out. Also when they burnt out it can cause the electrics to trip out.
To access the switch you need to remove the hob top. Remove all the burners and either side of each burner is 2 or 4 small screws. Remove these and then remove the screws at the back and then on the front holding it to the control panel and then you can remove the top. It can be a bit tricky getting this off.
Once its off you will see the selector switch. Check this and see if theres any signs of burning on there. If so then that needs to be replaced and the wiring repaired.
As if the clock is set then its not in auto mode so the oven or the grill should come on. At lest the little red light should come on.
So check that switch and see what you find and let me know.
there is no sign of burning on or around selector switch
Ok looking at the wiring going from the clock you will see a relay on there one side will be live linking from the live feed to the clock and the other side will go to the selector switch.
If you have a multimeter check that and see if you have 240v going from the timer to the switch.
sorry hav.nt got a multimeter but checked with a neon screwdriver power going into relay but none coming out to selector
Ok how many wires are on the back of the clock?
And is it just one relay on there with the 2 wires going to it?
one wire to selector grey . two wires in to relay pink. one wire from relay to selector pink. i think only one relay which is oblong shape , underneath this there is a disc shaped object .
I don't suppose you can post a picture of the back of the timer with the wiring on here can you?