Upvote:3
Visa required, except for Passengers with a residence permit issued by Slovenia for a maximum stay of 90 days [in a 180-day period].
Doesn't matter if it was issued on the basis of a family relation.
Visa required, except for Passengers with a "Family Member" Residence Card marked "Permanent Residence Card of a Family Member of a Union Citizen or Residence Card of a Family Member of a Union Citizen issued by Slovenia to family members of an EEA national or national of Switzerland if traveling with or traveling to join the EEA national or national of Switzerland.
So just present your passport and residence card to Uk immigration