wiring bathroom mirror from light switch

im looking to take power from my bathroom light switch to power bathroom mirror / demister. Behind my light switch I have a set of neutrals (Blue and Black) in a terminal block and also some earths in a terminal block. Im planning in taking a connection from the Neutral and Earth terminal blocks and my live from COM connection on the light switch, the last time I had to do this there was also a set of lives in a terminal block behind the light switch, this is not the case therefore im assuming I take the connection from the COM connection on light switch, as this should be permanent live. Thanks.

 

That's correct.