Bike lights help you to see, be seen and they're also a legal requirement when cycling at night (red at the rear, white at the front), so they're a pretty good idea! We have loads of lights to choose from with different power options, different sizes, different attachments and a range of prices so you should have no problem getting one that lights up your life.
Reflectors are a great way to help you be seen at night, and are a legal requirement if you're riding on the roads after dark. They don't take any batteries, so are a really cheap and easy way to make yourself more visible to other road users alongside your lights. Be safe, be seen!