Can signal providers post about their own trading profits, whether its trading view / meta trader etc. if so what do they need to say and/or what disclaimers (if any) are necessary,

You can only share trading performance using the "share function" in the Pelican App.

You are not able to take any form of screenshot of trading performance and post them in other social media. If you choose to do this you are liable to be sanctioned by the Financial Conduct Authority.