You don't need to renew Family Permit, in fact it's not actually possible.
The very important is the Residence Card.
For those who already applied they will receive a Certificate of Application (COA) which in principle is meant to prove your status.
Without either COA or resident card you will face some significant challenges to travel outside of UK and major issue when you try to re-enter UK.
I would very strongly suggest you contact UKBA to explain your circumstances and that you wish to travel to Poland and ask how they can help you.
Application of Residence Card is currently taking up to 6 months to process.
Please contact UKBA for advice before making travel plans with Residence Card or COA
