self employed, “sacked” and withhold last wage? UK based

So I'm a self enployer dancer innthe UK and have just been sacked from my club for “keeping tips” – which would be legally mine anyway – and for which they also never showed proof and when I asked they refused to do so, and on top they refused to pay me my last wage – surely that can't be legal, what can I do? I'm in Scotland. Appreciate any advice