The legislation is going to be your main hurdle - setting up a business is so simple in comparison. A great source of info here
https://www.lowimpact.org/starting-your-own-business-how-to-sell-hand-made-soaps/
Much of the requirement of the law concerns the safety of the individual ingredients, and most off the shelf ones you may be buying - the oil itself if commercially made - will already have the data sheets you need. Anything you make totally yourself, like from herbs you grow, might be more tricky. You'd need to be able to prove the variety of Basil (I'm making this up, obviously) you grow is the same as the variety you managed to find the chemical composition of.
A few years back, I experimented with fog fluid for the smoke machines I have, because the commercial stuff is very expensive, and I figured I could buy the components individually and make my own - for my own use, not for resale. Then I discovered a data sheet for one of the constituents that appeared to suggest it could under some circumstances (being burnt) be carcinogenic. The data concluded that when atomised it was safe, but when burnt it was not. The machine I had at that time squirted the fluid onto a hot element to produce the smoke, so was it merely heated (ok) or was it burnt? I frankly, I didn't know - so I abandoned the idea.
If you look at data sheets for vegetable oil it seems harmless, although, this example of a data sheet from Australia contains the usual "what to do" sections you'd have to produce.
http://www.wilmar-international.com.../07/SDS-Food-Grade-Refined-Vegetable-Oils.pdf
I discovered most oils used in herbal remedies all have these safety sheets available, so as long as you use known ingredients, you should be able to produce all the information the law requires you to have, but it looks like it just means a bit of hard work, and investigative skills.
If this doesn't put you off - you could have a nice, quite individual product to sell. Understanding the legislation will be the key. Good luck.
