is it possible to get his permanent passport and pesel number in uk without going Poland ?
Yes it is possible, and I know this because I went through the procedure for my own child who was also born abroad.
In addition to getting the temporary passport (I assume with 1 year validity?) you will need to go to the Polish embassy or consulate and fill + sign some forms, at least three times - once to apply for the Polish birth certificate, another time to apply for the PESEL number, and another time to apply for a regular passport. They are separate procedures, and the birth certificate must be issued and received before you can apply for the PESEL, which in turn must be issued before you can apply for a regular passport. For some documents BOTH parents must be present to sign at the embassy, so it is better if both of you go together each time.
However it takes a rather long time. From the day we filed the first application to the day we received a regular passport it took about 8 months.
finally, I did this 3 years ago and I cannot guarantee procedures have not changed since! Ask at the embassy.
If you are able to travel to Poland (either parent) the entire procedure can be done within 2 weeks. The UK birth certificate translated to Polish and attested plus a certified (by a notary) and attested (by Foreign Ministry + Polish Embassy) copy of the non-Polish parent's passport needs to be presented. Ask your spouse to call the registration office in their area and ask what are the current document requirements.