Hi June.
No official registration needed for a famiy carer in the UK ... most of us are " Invisible. "
Practically , two places spring to mind for others to know of the existence of the carer / caree relationship ... local gp surgery ( Possible " Carers " person nominated to fast track carers ? ) and your local social services.
Having some form of emergency card with short details thereon also advised ... should anything happen to the carer , what of the caree ? ... especially in lone carer situations.
Financial situation noted ... a rare occasion in CarerLand ... wherein finances , or lack thereof , is the number one problem.