Hello!
"Separate Charges and Transfers" is where your Customer would make one purchase on your Platform account, and your Platform is then responsible for creating Transfers to the respective Connect accounts where the Customer purchased from.
There is a limitation here, in that you can only use Separate Charges and Transfers for Connect accounts in the EU, as a UK Platform.
The alternative here to support Connect accounts beyond the EU would be to use "Direct Charges'":
https://stripe.com/docs/connect/direct-charges. "Direct Charges" are not limited by region because your Platform is creating payments directly on Connect accounts.
In the "Direct Charges" model, your platform creates PaymentIntents directly on the Connect account. One limitation here is that if you have a Customer purchasing from 2 Connect accounts, you cannot bundle it as one payment, this would be two distinct PaymentIntents on two different Connect accounts.
Cheers!
Ali