I saw that Thai showers only use 3kw so decided that they would be  ideal to use in the small  office/studio I have in the UK. I purchased one and took it to the UK and installed it but it does not work. The shower works fine but the electrics are not working so no hot water.  My question is are they not compatible with UK electrical system or could it be I have a faulty one? Or is it possible that the installation was done incorrectly?  Thanks for your Help.

It should work just fine.

 

So bad installation (unusual for the UK), it's duff, or maybe pilot error (you did rest any internal RCD?).

 

 

As said sounds as if the ELCB is tripped if electric is confirmed to be getting to the unit.  But even if it works you are probably not going to be happy with the heating as suspect the normal water temperature in UK is far below that here in Thailand.  Even here the 3k units are not enough for most people during cool season in Chiang Mai, even with low water flow - and the UK is a whole lot colder than Chiang Mai.