Describe the impact on a developed donor country as a result of an increase in migration

One benefit to Poland’s population reducing due to migration to the UK would be that it relieves pressure on local services such as healthcare and schools. This means that they would have more money to evenly spend on their remaining population and increase the standard of living. Another benefit would be that when migrants send back money to families etc from the UK to Poland, it would bring more money into the economy.
However, one disadvantage would be that Poland would experience a ‘brain drain’ meaning that they would lose skilled workers and have to retrain many people. Another disadvantage, contrary to the potential benefit would be that it could potentially be damaging to the economy as less wealth is generated to pay for vital services such as health care.