It really depends on what treatments and how much they are spending.
If they only want a manicue and they live more than 5mils away i would charge a min fee.. whatever your average per hour is how one way you could work it out, as you have to consider traveling time & petrol there & back, howerever if they are spending £30 upwards and your going to be there a while, i wouldn't charge. but i would make it clear when you get there, that if they DO only want one treatment in the future there will be a charge, but if they get a few friends together there wont be. That way it'l boost your clientell coz they'l want to save money.
Hope his helps
Foundations answer sounds good to me, just wanted to add that when I work out millage for one of my drivers, I give him 39p per mile, this is supposed to cover his fuel, wear and tear which with the fuel increases I think is on the light side, with the fuel hikes if I was working this out for my self it would have to be 45p per mile after the first 5 miles. Hope this helps.:hug: