I've done First Class 3 or 4 times in a Voyager (first time was on the 11/03/17 but on journeys under 3 hours.
I can't resist saying that First Class may be spacious on the Voyagers but on the HST's it's more roomier - the 11:17 from Birmingham New Street to Bristol Temple Meads on the 18/02/19 I went First Class on a XC HST. I had seat number 4 in Coach A booked. That one has 2 seats next to you and no seats opposite. The floor opposite the wheelchair space is for luggage!