Hiya @dollz (Elliot) & Welcome to the Cuckoo Community !!!
Just to add to @jakes comment above which is actually true the router itself will be programmed with one set of account details and this would also require manually changing these details over if you moved between propertys and lines and indeed had two cuckoo accounts as the connection account is associated with a specific line.
So basically one account per line/router.
I see where your possible logic is coming from however thinking that the router will just work like a 4G Based Hotspot between the two properties.
If its a One Time Move eg…Moving Home From London To Devon then indeed the Cuckoo HomeMove Transfer can be done from within the Cuckoo Online Account if the Devon OpenReach Network is Available to connect you and it would just be a phone number change and setting up your services at the new property this would take up to 14 working days to arrange so unfortunately not Plug & Play.
But the Home Move Transfer is the only way the Cuckoo Router can be used at another property otherwise.
4G/5G Hubs that use the mobile phone networks signal and transmitters dont require this Lockdown however so its just a case of turning one on to connect too and watching your limited data allowance being used on whatever plan you have chosen with a particular provider.
Hope This Helps & also thanks for the Question !!!