I saw what appeared to be some 5-car 801s standing at Tyne Yard earlier in the week (I saw the 801 part of the number out of the window, I was travelling on another train at the time so I only had a few seconds of view); was that the 5-car 801s (801/1s)?
I'm sure I saw one pan-up as well at Newcastle, but as I was waiting to board a train I wasn't in much of a position to take a photo or get whether it was an 800 or 801. Also they will need to have some 801s running somewhere in order to have enough combined 800 and 801 units to reach Newcastle, let alone Scotland. Also there will surely be know-how from the GWR 800s and 802s, which can be used to iron out issues at the manufacturing stage.
There is 4 sets of 5 car 801s stored at Tyne yard at the moment.
I believe they are still testing 5/10 cars joining and splitting, to get the passenger information and reservations systems working correctly, something which I believe still causes massive issues on Gwr.