Could I just ask when would I know to get the ball rolling with this? Like will they notify me via letter etc.
They are obliged by law to send you postal notification of debt registration in the form of an Order for Recovery, (OfR). Unfortunately, experience of this forum is that post can be seriously delayed or it never arrives, and this stage is crucial, as it's the final stage before bailiffs can be instructed. This is why you must be pro-active and not just sit around waiting for the OfR to arrive.
So after the period for payment of the CC expires, you need to check whether the debt has been registered by phoning TEC about every 7-10 days to enquire if it's registered. As soon as it has, you can download the Witness Statement form from the TEC website. The form should also be included with the OfR. All it needs is filling in the details and sendin off, email is best, (photo of the completed form).
If you can view your PCN on their website, it usually tells you the amount owing, so when this gets to £250, you know the debt is registered. This is an alternative to phoning TEC.