Sarah —

You may go to Mass and Holy Communion, only if there is no Roman Catholic Church within a reasonable distance. The Polish National Catholic Church is a schismatic denomination, not in union with Rome, and in opposition to Church teaching in the case of contraception, however,
like the Orthodox Churches, it has retained valid Holy Orders, so its Mass is valid.

In Canon 844, #2, the Church states:

"Whenever necessity requires or genuine spiritual advantage suggests, and provided that the danger of error or indifferentism is avoided, it is lawful for the faithful for whom it is physically or morally impossible to approach a Catholic minister, to receive the sacraments of Penance, Eucharist, and Anointing of the Sick from non-Catholic ministers in whose churches these sacraments are valid."

Mary Ann