I know it's a stretch, but can we use a family member's UK home address as a legal address for the Global Card transfers? We will probably be staying there anyway for a time as we figure things out.
On the website it says:
Apply for your new Card online:
1. Select your preferred Card from our All Cards page.
2. Click to apply online.
3. Please complete the application with your existing Card number, UK home address, UK home
phone number and previous home address.
4. We’ll contact you within a week for ID documentation and any additional information, if required.
5. Once approved we will send you your new Card.
6. Please call the number on your old Card to transfer Membership Reward points, or if you wish to cancel your old Card.
I don't remember having to show a proof of address or anything to be honest. If they ask for proof of address then just wait until you get here to do it, get proof of address by getting your provisional licence or from HMRC when you request your National Insurance Number. Either way, it was seamless and got me started straight away. It was also good, because I avoided online statements, and it gave me proof of address for other things, including the correspondence requirement for FLR (M) and Set (M). IIRC, I just filled out the form and then they sent it straight away.