Do I need to visit a branch to open my account?

No. Biscuit is a fully digital, app-only current account. Zopa doesn’t have physical branches. 

You can apply, verify your identity, and manage your account entirely from the Zopa app on your smartphone.

Because there are no branches, you can't pay in cash. You can add money by bank transfer instead – see How do I add money to my account? for how to do this.