CDC question

Don't think this has been asked before, if so apologies....

We'll be using miles as we normally do for a chauffeur drive car between home and LHR on our next UC flight. If there are three of us on the booking, two of us in UC and one in Economy will our friend in Ec be allowed to share the car with us? I was thinking that almost certainly he wouldn't be allowed to be checked in at Drive-Thru but perhaps would simply be allowed to get a lift with us and be dropped off outside T3?

Thanks
James

Actually your friend can use the car (subject to being enough space) and use drive-thru and go to the clubhouse with you... SCORE!