Bathroom with remote switch

[FGoogle]

If I were to rewire my bathroom:

1. remove all current wires
2. Add a light wired directly to the basement and plugged into the ring mains
3. Added a remote switch Like:

I breaking any regs?

Would I still need Part P certification for this bit as it is technically just plugged into the ring mains?

MN

[Dave Plowman (News)]

Why bother? The only time Part Pee might come up is when you sell the house - and a bodge like that would be more of a problem.

[FGoogle]

I was more worried about the regs than Part P - It is under full building control for Part P.

It sounds like a bodge - but what exactly is wrong with it?