What's the correct rating to look out for in a bathroom wall heater?

[LeanTwo]

I am just in the process of a bathroom refurbishment and I am thinking of adding a wall heater.  Many are advertised but not all state a safety rating that the heater complies to.  What is the appropriate safety rating for a wall mounted bathroom heater (Fan or infrared).  It's the instant heat type of heater that Iam looking for rather than an oil circulation radiator type.

 

Any information, thoughts or advice would be great.