[Replacement Thermal Pads]

Is the Pi Hut your distributor for Canada too?  I

[Replacement Thermal Pads]

Love the case.  My question is swapping/replacing boards in the case.  I have the 2nd gen case with a RPI Model 3B, I want to swap it out and with a Model 3B+.  I hear the thermal pad will need to be replaced with a thinner pad.  

Where can I get thermal pads for both  Model 3B or Model 3B+ (I live in Canada)?

What should I be looking for?  

P.s. I not much of a hardware guy, so I don't have any experience with Thermal Paste/Grease.   Is this a good alternative?  Please advise.