If your parents lived in Green Lane, then the English Martyrs' Church in St George's Road, Wallasey would be their parish church.
Contact details :-
Phone 0151 638 3066
Fax 0845 299 1768
However there are no graves around the church so it may be that the suggestion that your brother is buried in the Catholic part of a cemetery is right. Landican Cemetery hold the records for the Wirral Cemetery's so it would be worth contacting them. Its possible he is buried in either Earlston Cemetery, Wallasey, or Frankby Cemetery, Greasby.