Hello Odcecki,
I have searched the Polish Army Records and the index of victims of soviet repression all without any joy in finding your Grandfather listed, therefore I would suggest that you apply to the British Ministry of Defence to obtain copies of all records that they hold (be sure to request copies of all records that they hold, otherwise you will just receive either a 1 or 2 page letter out lining his service and personal details).
Unfortunately they do charge for this service now, just click on the link below :
Get a copy of military service records: Apply for the records of someone who's deceased - GOV.UK
Once again Welcome and best wishes for your search
Andrzej
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