Big thanks for all the advice guys,
I actually attempt to talk to her in person at her door (didn't step over the threshold) regarding the more important subject of contact with my son etc. And if I could have him stay with me for a few days. This was shot down straight away with lies about Children Services saying I'm not allowed to see him at all until Parenting Assessments are done etc. (No cautions against me or anything like that) I even called both 101 and Children's Services to ask if me going over there to talk to her regarding contact would go against me and they both said no.
Anyway, she gets on the subject of giving me my gun if I pay her money for it, I ask where it is and she tells me she's given it to her older brother and it's currently at his house! So now I have no idea if this is correct or not. But she's given it away to someone else and it's currently in their possession.