Insurance to practice hypnosis is typically very low, as it is seen to be a safe, non-invasive therapy. It is important to have insurance in place, as you never know what may happen, or what a client could allege. Offering treatment to people opens you up to the possibility of a claim. With comprehensive cover in the region of €100 per year, it's well worth getting yourself covered.
Be sure to check the levels of cover offered. The cheapest is rarely the best.