In it's most simplistic version, you should do something along the lines of the following
Firstly, work out what your base rate is.
Add all your costs other than products and desired wage.
For example; rent at £100/week is £2.5 per hour based on a 40 hour week.
Nail tech insurance at £60/year is 3p per hour based on a 48 week year and 40 hour week.
Then you have all your other bills and costs to work out.
Your base rate is currently £2.53 per hour.
Say you want to make £20 per hour, you're now at £22.53 per hour of treatment. This is what you need to charge to cover your time and other costs, per hour.
So, if a file and polish takes half an hour, you would charge £11.27 + product costs (50p?) = £11.77; or £12 for ease.
As an example, I charge £28 for a shellac manicure/pedicure. I charge £30 for a pedicure and £10 if my client wants shellac on top.
It's far better (for you) to charge higher prices than to compete with cheap salons in the hope of getting their clients.
Finally, I would advise you to put away 30% of your takings to put towards your tax bill. Putting it away as and when you get it means you don't need to scramble to find enough to cover what could be a large tax bill.