To move funds from your Classic account to your Growth Street ISA, you will have to withdraw the funds to your external bank account and then deposit them into your ISA account. Please remember to include the Payment reference when depositing into your ISA.
You will need to turn off your reinvestment settings and wait until your loans are repaid to your holding account before you can withdraw your funds. We would recommend you transfer funds as they become available in your holding account (rather than waiting for all your loans to be repaid), to ensure your funds are consistently deployed.
Also, keep in mind that in order to remain eligible for any bonus connected to funds in your Growth Street Classic account, you must redeposit the funds to your Growth Street ISA within 48hrs from when your withdrawal is processed.
Your capital is at risk when you lend to businesses. Find out more here.