Most likely only from a caravan breaker as the fire would be past it's sell by date for spares to be still available. However try this site 
www.preloved.co.uk  no I'm not joking either I have the site on my favourites in case I need it, but so far had satisfactory replies from this forum.
Don't forget this site as someone may reply who knows where. I've got the same c/van same year. No you can't have my heater.
                
 Bob
                
 May 2010