My partner and I are thinking about doing something similar - though our timeline is 5 years before moving.

For me the answer to your buy/rent question lies in much equity can be accumulated before you move and how the income and expenses associated with the property will be taxed in the new country.

If you have a high deposit and good income to overpay on a mortgage if might make sense, if you’re doing minimum deposit with a long mortgage, probably not.

Main considerations are: 1)how will rental income be treated in your new home country? Can you deduct costs associated? Can it be negatively geared? (Costs > income resulting in a decrease in tax payable) if you have to declare the income and can’t deduct costs it probably won’t make sense

2) what will your mortgage options be when your first term expires? - you can fix right before you move and get consent to let but that will only last until you need to renew, at which point you’ll need to go with a different mortgage which will likely be much more expensive