It will depend on the type of chemo drug whether you lose all of your hair or it thins. My hair thinned and became very much like Brilllo, but is now, 2 years in remission, back to normal. Other people with my cancer but on different chemo treatment as there are 60 different types of my blood cancer, lost all their hair. Most of those people said they had their hair cut short before treatment started and then had it shaved off which was less distressing than it falling out, made them feel in control and was more comfortable. They then chose beanie hats, scarves, turbans or wigs. Some hats come with false fringes. All say that once treatment finishes the hair grows back quite quickly. Sometimes curly for a while.
Whichever cancer you have will have a support line and they will be able to help with lots of advice. Macmillan wil be very helpful as well. Good luck with your treatmentX