How are non-UK based investors taxed at Source for any cur8 deals

I am struggling to find one answer to how different investments are taxed at source (UK) for non-UK /International members. I mean I do not have UK Tax id/Bank account /any finance history in the UK, when the fund matures/individual deal is excited how do you calculate tax and how do I repatriate the funds back to my country.

Eg: I invest in Godwin deal 100$ and gain 120$ , so as foreign investor how do you tax me at source once when godwin shares the exit money. The same question can be applied to the EIS/Raed scheme.

Jazakallah