if you want to maintain a very British life style
There's really not that much difference. Both places have malls, people in both countries have clothes, pay bills, drive and/or use public transport, use uber eats, get their hair cropped and take weekend breaks if they can afford it.. Bills, travel and beer in cheap bars are cheaper here; most other things aren't that different.
The diet is poorer and less varied here though, in large part due to income levels. It's not extravagant to eat well though and Poles do enjoy going to the theatre or opera, to the cinema and when we go for weekends away here, we stay in nice hotels where the other guests are generally Poles.
or at least show him how it can work.
You can save money on some things though, and it is worth doing. Waiting in a massive queue to get the 25zl 'sunny express' train ticket that takes 4 hours or paying 75zl for a ticket on a quicker and less crowded train is however not.
It used to be cheaper here, however costs are noticeably rising in cities as living standards improve.