How do I fix my newworld gas cooker?

I have a new world slimline gas oven, grille and hob and the grille seems to go out when i release pressure on the knob unless I first light the oven. Also the oven doesn;t seem to get hot at all asside from a slightly warm pilot light thats visible. Am i right in thinking that both problems might be fixed with a new thermocouple?

Mike
June 2008