Hey @SHRIMPERPETER, thanks for the post.
When you leave EE, you can request a PAC code off them, which we will then put in our systems and transfer over the mobile number. This can be done anytime, when taking out a new SIM or even months later, should you wish to retain your old number. The PAC however will expire 30 days after it's been issued.
So whenever you'd like to, get the PAC code of EE, and when placing an order with Virgin Media you can even give it to agent who will be able to get it transferred over for you.
Thank you, let us know if you have anymore questions - happy to assist 🙂