Hi Antony and welcome to the Disney Parks Moms Panel.
It's always lovely to be able to answer a question from a fellow Brit!
You can absolutely collect your
MagicBands (which will be magically waiting for you) from your
Disney Resort hotel as soon as you arrive, regardless of whether your room is ready for you at that point, or not.
Once you have collected them, you are free to head off to enjoy your day at the Theme Parks!
If your room is not ready, you will be able to leave any luggage that you have with you at Bell Services until you return to your hotel later that day/evening.
If I can be of any further assistance with the planning of your upcoming visit, please feel free to ask me another question.
Wishing you a magical holiday filled with memories which will last a lifetime!
Emma