Not sure is the short answer.
AOTN is very close to the A1 and it's junction at Allerdene, and is a magnate for people to visit, it being a prominent landmark. I have visited it myself a few years ago but not with a drone and, from what I can remember, I think that in 'normal' times it was flyable at times where there were fewer visitors. Generally, though, I would see it as a 'congested' area because of the number of visitors it generally attracts. To fly it, then, I think that one would have to do it early morning.
All this I say without having researched the site with a drone flight in mind. Researching it may throw up issues with the local authority or with whoever actually owns the land it stands on. There is public access to the site but I don't know if the land is privately owned. However, there is a playing field whose Southern edge boarders the Northern edge of the AOTN site. If I were looking to fly the AOTN, then, I would be looking at that playing field as my take-off site. Go into Google Earth and search 'Angel Of The North, Gateshead', and you will see what I mean.