With free standing lights, there’s not really a whole lot that can go wrong - just plug them in and hey presto, let there be light. With fitted lights, it’s a different story.
Live mains are no joke, and if you make a mistake, you risk serious injury, potentially death, and could quite easily burn your house down. Even if you’re a pretty handy guy, it really is worth getting an electrician to fit your lights, it’ll certainly be cheaper than a new house should something go wrong!