you may or may not be aware that The owners of UKTV (BBC & Discovery) have had a carve up and have moved Really, Home & Food under Discovery's wing, these channels are no longer available on UKTV Play and as such are no longer available to catchup on Freeview Play.
I only discovered all this yesterday as my Wife had forgotten to record a program and couldn't find it on UKTV Play.
Discovery have launched a new player dplay which has these channels along with Quest and a few others, but this is not available on Smart TV's and as such not on Youview. Their App is available on Apple or Android.
I did email discovery firstname.lastname@example.org i am not encouraged by the response that their player will be made available to smart TV's or be integrated with Freeview Play.
Maybe BT/Plusnet/TalkTalk would be able to exert a bit of pressure and try and get a copy of the dplay app added to the Youview Platform?