Which mortgage you should choose depends on several factors including your attitude toward risk, what you think will happen to interest rates and how much you like certainty.
If you want to know what your repayments will be each month, then fixing is a good option, but you still need to consider how long to fix for. A two-year fix gives you some security, but for a short time period.
Shorter fixes are good if you think you might move home fairly soon. Not only will your fixed term end sooner, but the penalties are usually lower if you choose to pay off your mortgage before the term ends.
However, if you think interest rates will go up over the next few years, then you might face a sharp jump in repayments when the deal runs out. A two-year fix also means you'll likely want to remortgage in two years and there are fees associated with doing this.
Longer fixes give you certainty for a lengthier period and mean you’ll remortgage less frequently so those costs will be lower. But fixing for longer usually means signing up to a more expensive deal.
With a variable mortgage, when interest rates drop, mortgage repayments will too. But, with a fixed-rate mortgage, they'll stay the same – as you're locked into your deal. You might then feel like you're paying more than you should be for your mortgage.
Variable rates are also generally cheaper initially, so if you’re confident rates will stay low, or you can afford small increases in repayments, this might be a better choice for you. However, you do need to make sure you could afford the payments if rates were to rise significantly.
If you want to fix but think interest rates will fall, a shorter fix might be better than a longer one as you can move to a cheaper deal sooner.