Batteries *and* charger from a reputable UK source.
Never charge unattended.
Get a lipo charging bag or charge somewhere with non flammable furniture/surfaces, and in the house… working smoke alarm!
Google the incidents of exploding batteries.
Job done.
The light, wherever you like. There is a bit of you get what you pay for. The basic LEDs inside are mostly all Cree and same Chinese or UK sourced (except the fake ones 😉 ). The difference is in the build quality, the driver board (and how it adapts to battery level & temperature… or not), settings available, ease of use, mount options & flexibility, weather proofing, along with the lens and reflector quality which make a huge difference in the actual brightness and spread or focus (depending if you want spread or spot. Cheap lights may not give you an option).
Finally… ignore quoted lumens.