If you do decide to choose a fixed rate mortgage then you need to decide how long to fix for. You can fix for a short period e.g. 2 years. However, if you want security over a longer period then you’ll likely pay a higher interest rate.
No one has a crystal ball and your mortgage broker may advise you on length but he or she can’t make that decision for you. If you are worried about whether you can afford your mortgage then fixing for longer can give you some security, but at a cost. Rates have been low for several years now but eventually they will inevitably rise, so it’s important to factor that into your thinking.