The salary for a sales assistant will depend a great deal on where you work. In my local area, you can earn anything from £6.50 an hour to £10 an hour just from the shops on the high street, so there’s nothing to say that you will definitely get a low wage. You might also find that you’re able to get small amounts of commission as well, which should help you. But on the whole it is so variable that you would be better asking companies directly what they pay if you are interested in working for them.