USB from light switch

Can’t come off the light switch as there is no neutral there. Suggest an electrician has a look.

It depends on whether there is a neutral available at the light switch/switches concerned. Some lighting circuits are wired to loop the line and neutral conductors to each lighting position and some are wired to loop the line and neutral to each switch position. You can't tell by looking at the switch plate; the switch plate has to be unscrewed to discover not only the answer to this question but also whether the back box is deep enough to be used for grid plate style switching. 'Power' is usually associated with socket outlet circuits but I can't see why this can't be done by a competent/qualified person (neutral/space providing) who would know the associated tasks to be taken to ensure a safe installation.

I recommend that you use a qualified and competent electrician with the correct insurance in-place that is also registered with a Competent Persons Scheme

Generally older installations are more likely NOT to have a neutral at a switch. In a newer installation you will most likely have a switch fed with a neutral and permanent live, it’s important to check though to see. If you do have one you’ll need to fuse it down From 6amp of course. An electrician could do that job for you and more than likely set you up with a grid switch which will be fused and have usb modules. Tbh I expect that would look pretty smart once done. What you’ve creating is a smart home hub controlled from these points and potentially voice ( ceri ) activated. On another note… when it’s mounted try and keep a good void behind for air flow, keeping the pad cool is important. I wouldn’t recommend it above a radiator if it’s going to be plugged in permanently. I do like your idea though, contact me again if you have any other questions about taking the system further.