A lasting power of attorney is now the appropriate power to take. There are two types 1) Health & Welfare - which deals with the practicalities of her care (medical decisions, accommodation etc) and 2) financial affairs - this allows the attorneys to manage the person finances and property (eg. paying bills, accommodation, collecting income/benefits), this power (depending on the her instructions) could be used either before or after she loses the mental capacity to make decisions for herself.
They are all dealt with through the Office of the Public Guardian. She, donor, would obviously have to be the one making the application. The forms are available for download from the OPG website and I attach link to the page for LPAs and you will see there is lots of useful information, including guidance notes:-
It would be best, XXXXX XXXXX of the application being successful and avoiding any suggestion of impropriety, for a solicitor to make the application after having taken her instructions. It should cost around £400.00+ Vat in legal fees and the OPG fee is around £300.00 for each power.
If despite the fact that you are some distance away you think you might be able to manage her finances adequately from a distance then she may choose to nominate you as an attorney(ies). If not then it may be more appropriate to also select a solicitor in her area or another very trust-wroth individual.
You can find solicitors in your area or that of your mother's by entering the postcode and selecting "wills and probate" from the drop down menu (they will all have solicitors dealing with LPAs):-
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