another house or decent flat as a rental, would this provide a decent base income?
How much you expect from one home in Poland? Better buy home in London and live in small flat in Poland.
My wife is a teacher and would go back to this
Teacher is not a dentist.
but my polish is very poor
Do you expect a sharp improvement when in Poland?
Think why we leave comfortable homes, flats, cars, gardens, lakes, forests and decide to live in London? For income. Income is crucial. Not a cheap country.