Thetford use a magnetically operated reed-switch to control the light and isn't a visible switch such as the type in a domestic fridge. The reed part of the switch becomes permanently magnetised and becomes stuck on, hence your problem.
Can you advise on model of fridge and I can find drawings for parts. Model number will be shown on a label inside of the fridge, usually down near bottom and you might need to remove draw to view.
As well is two words!
How does a sage know everything about everything? or does he? or does he just think he does?
Remember, if you buy something you bought it, not brought it.
I had the same problem, bulb getting really hot. I took the same approach as tentz suggests - I can see in all my other cupboards without a bulb in there so why should the fridge be any different? Hasn't been a problem
To be honest, Tentz suggestion of removing the bulb will be the easiest be far. The reed switches do fail as I've already mentioned, however depending on model, they can be an absolute pig to replace.
I use my fridge without a light without any problem.