If the clock is not working this would indicate that there is no power, check the trip switch (MCB) on the consumer board. Are any other sockets/ appliances affected? The oven may be plugged into a socket behind the unit, see if you can check the cartridge fuse on this plug, it may have blown. The plug may not be readily visible, have a good look around in the back of the units. Once you have power the gas flow may return- some modern cookers have an automatic gas shut off which will cut of gas supply if the electric ignitor will not ignite the gas. It's unlikely that the gas supply is at fault per se given that the hob is ok.