No thermostat gasket, what to use?

I bought an OEM thermostat for like £30, and it doesn't even come with a gasket!
Really annoyed about that as that was partly the point of buying OEM. The non-oem thermostat I originally tried had a rubber gasket attached, but it was so hard I snapped the flange tightening it on.
I have some paper gaskets from another non-oem thermostat.
Will a paper gasket do? Will it not leak? Does it just go on dry? Do I need to get some sort of rubber O-ring? Is it a good idea to mix the paper one with some sort of liquid gasket? Or should I just use liquid gasket alone?
Bit lost on the best way, I really need to get this done with no leaks first time as MOT is in a few days.
Cheers.
 
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