It’s within the Sefton Coast SSSI. I’m not convinced by what you have been told. It’s an offence to recklessly damage, destroy or disturb any of the designated features of a SSSI (which at Sefton includes various birds), but it’s not automatically an offence to fly over or within it. There are specific prohibitions at Sefton on “recreational activities likely to damage or disturb species of interest”, but these are prohibitions on operations carried out or permitted by the owner or occupier of the land.
All assuming there is no specific anti-drone byelaw in place, then so long as you don’t disturb the wildlife, then at most the landowner (Sefton Council?) could ask you to move on.
You could:
- Fly anyway, plead ignorance, see what happens. This is what airlines are doing every time they fly over this site. Nobody is stopping them.
- Notify whoever contacted you that you will be making another flight and request confirmation of precisely what regulation they plan to prosecute you under, or to demand permission under. It’s just bullshit if the best they can come up with is “it’s not allowed”.