I am a non EU national but I have a EU family member permit issued in UK as my wife is a German national but living in UK from last 15-20 years.
I am an Indian and the permit was issued in UK. Permit says family member of an EU national and work activities allowed.
We are travelling to Germany together by car but on the way back I am flying by myself.
Do I need a visa to enter UK or not?
You have a UK residence permit. I assume that it is valid. With a valid residence pemit, you do not need a visa to enter the UK.
Among other visa exemptions from TIMATIC, you will find this:
Visa required, except for Passengers with an EEA Family Residence Card issued by the United Kingdom.
One source for TIMATIC data is https://www.klm.com/travel/gb_en/prepare_for_travel/travel_planning/travel_clinic/visaform.htm
