Wall mount tablet power idea

Hello clever electrical experts, non-qualified DIYer here looking for someone advice, please.

I am looking to install a wall-mounted tablet I er my light switch to control smart home stiff like lights, radiators, etc. I have an idea about how to run power to the tablet without ripping open my walls, but unsure about whether it is safe to do this on my lighting circuit.

I want to replace my existing light switch with a 2x euro module faceplate containing:

• A switch like this,
  

• A USB charger like this. 
  

I'll build a frame of some sort to mount the tablet over the wall plate and hide a short USB-C cable so it all looks clean.

I'll need to leave the light switch on all the time to be able to control the smart bulb. I want to wire the switch and the USB charger in series so that the USB port provides power to the to tablet as long as the light switch is on. Is this safe/legal?

Any ideas are very much appreciated! 

If you have a neutral at the switch this may be possible. 

If you don't have a neutral at the switch - not possible

PS just because you can see a black or blue cable at the switch doesn't mean you have a neutral

Thanks for the quick response, Murdoch.

I did wonder whether I needed a neutral, but the USB charger only takes two wires:

Connections: Fit the unit to the Wall Plate before making any connections. Strip the wires to expose 7 to 8mm of copper conductor Connect the Brown or Red wire to the terminal marked "L" Connect the Blue or Black wire to the terminal marked "N" Ensure that the earth wire (Green / Yellow sleeve) is securely connected to the metal mounting box used in the installation. Do Not Megga Test

Click to expand...

I wonder if I can wire this like this:

Live cable >> Switch COM

Switch L1 >> USB L

USB N >> Bulb

Please excuse my ignorance of I've got my wires crossed (no pun intended)!

NO that won't work.

Amar said:

I did wonder whether I needed a neutral, but the USB charger only takes two wires:

Click to expand...

the charger does take 2 wires... one being a neutal... your idea will not work

Hmm, the old 'I've got a neutral at my switch' problem, reminds me of a call out a while back, 'I've wired in a new light and it's behaving oddly' said the customer on the phone. he'd connected a small lamp to the live and 'neutral' at the switch, turning on the small lamp caused it, and the centre light to glow dimly, turning on the centre light mad it go full brightness but the small lamp stopped glowing and went out.

I explained it all to him as to why it was doing what it did, 'well what a stupid idea putting a neutral at a switch if it isn't a neutral' was his reply. I really wondered if a bit of red sleeving on the switch wire would have really made any difference in this case, probably not, he had been told a black wire was always the neutral and that was that. A perfect example of why some people should leave things alone. lol