I can't advise directly, but we're also trying to deal with a European country inheritance law + British, so we've learned a bit. I am not a lawyer and as confused as you are probably.
Firstly, it's near impossible to get a UK lawyer of private law to comment on an international matter. We're paying a fair wack for a good lawyer, and they can't (legally, I presume) talk on foreign matters. We've had to pay to consult both foreign and UK lawyers, and keep checking between the two as we learn one thing in one jurisdiction that affects something in the other. As neither country's lawyer will give their full opinion, we're left to kind of figure out the next steps ourselves.
There's an added complication that most European inheritance law is under the Hague Convention, I think, and the UK always refused to sign that EU convention, so UK law is incompatible with the inheritance law in most EU countries. I have a feeling Poland is a Hague Convention signatory, but UK of course it not.
You're going to have to consult a Polish lawyer, but they are most likely practising in Poland. Who deals with your Polish IL's estate, they might be of use? In areas where there's a large Polish community you might have some luck on FB pages, asking for recommendations.