Thanks for the replies, they're all really helpful!!

I've literally just got my digital thermometer and hygrometer in the post so I'll set that up now.

I'll move my cold side hide into the corner when I get him out of it (still there). He does bask in the hot side, I've seen him go there a few times along with my whole tank being messed up in the morning lol.
I'll also definitely give the humidity producer thing a try, I've read it before on another forum.

Also, the thermostat is a dimming one so I'm not sure if that would work with the heat mat?