You are correct that self employed workers do not have the right to the minimum wage and as such you can pay them whatever rates you want. The key to them getting the NMW is to be classified as workers or employees. Whilst the Uber case is quite complex legally, the main reasons they were found to be workers, rather than self employed, was because Uber was deemed to exercise too much control over them when it came to the work they did and how they did it.
You will not be able to determine yourself with certainty whether the people working for you are workers or not – only a court can do that. If you are confident that you do not really exercise much control over their work and that they are genuinely free to choose what work they do and where they do it, then there is more of a likelihood that they are not workers, but self employed. However, nothing stops any of them to challenge you over this if they wanted to and it really depends on how much they want to fight this as to whether you may have to deal with it at any point in the future.
To be on the safest side, you can just bump up their rates a little bit to bring them in line with the NMW (The Living wage is just a recommendation, not legally binding), but I know many employers who would not do so and take the risk, which I would not say is that great in the circumstances.
I trust this has answered your query. Please take a second to leave a positive rating by selecting 3, 4 or 5 stars above - this is an important part of our process and recognises the time I have spent assisting you. If you still need me to clarify anything else, please reply on here and I will assist as best as I can. Thank you