Yes, you can use your credit or gift voucher to add the Ambassador Lounge to your visit.
To book, please visit https://www.atgtickets.com/theatre-packages/ambassador-lounge/ - Please ensure you select the same date and time as your tickets.
When you've selected your date, go through the checkout and when you reach 'Payment information', select to use a gift voucher.
You'll need both the voucher number and redemption code from your gift or credit voucher.