Hi and a warm welcome to you from all the Staff and Moderators. I'm not a lawyer; however, my take on this is that provided you're not "overfeeding" (i.e. constantly throwing out lots of bread and other kitchen-type waste and leaving it out on the ground), and the feeders aren't by their windows, washing, car etc, I cannot see he can complain really (though, of course, some people will always find something to complain about LOL).
Is the wall where he put the spikes 'his'? Or yours/jointly owned? You might have cause to complain about that if he did it without your agreement. Not sure you can do anything about them taking photographs, unless he photographs you/family members without your express permission.
All things Scottish can be found
here. Maybe you could post there about this issue, as one of our members may have some legal training, remember, that laws in England (and the rest of the world of course) could vary on this.
Also, keep an eye on threads titled something like Scottish Bashes; we try to meet up occasionally and they're always great fun. You'd be most welcome to join us on another if you can manage.
I'm sure you will enjoy it here and I look forward to hearing your news.