Ann: Shareholder Support and Instructions, page-538

If you have a broker who handles DRS transfers you can initiate the transfer with the letter.

@Flectional and @oldpa have been updating this is previous posts.

Otherwise wait for your code to be sent to activate CS account.

My choice after reading up and weighing up was to go back to my original broker for a Custodial fee each year.

The sales facility appears to take a long time with CS then waiting for payments also.
My opinion on not advice.