Hi - I was looking into adding lighting to my 10253 Big Ben. Most of the lighting I've seen just lights the Houses of Parliament section and not the tower. I've come across a system being sold by a place/person called Brick Booster in Hong Kong. The lights seem to be incorporated into actual Lego bricks. They are also made specifically for specific sets so he has other lighting ystems for other sets with bespoke pricing.
The Big Ben lighting seems expensive at £75, but I'd probably go for it if I knew some people on here have had positive experiences with this seller/product. The video of the ighting looks absolutely fantastic: