It's all in the timing
If you are planning to work abroad for a year or more, and want to minimise the UK tax due on your overseas earnings, you need to plan your departure date from the UK very carefully.
We know this is not always possible, but if you can stay out of the UK for a full tax year, that helps to make you 'not resident' in the UK for that year. If you are not resident for tax purposes, you are generally not taxed on your overseas earnings.
There are many factors to consider when determining whether you are tax resident in the UK or not, and new restrictions this year on the tax savings you can achieve while you are away. We will need to talk through your particular circumstances. You should also complete form P85 on your departure to reclaim any tax you have overpaid in the UK.