She needs to download the forms from the government website. There are two forms of POA, personal and financial, they cost about £78 each, and each needs a witness and a certificate provider. The certificate provider has to interview your aunt alone and without influences, to judge whether this is her own personal decision or not. If she is already "in a real muddle" she might be judged incapable of making the decision to appoint a POA.
ANyway, all the information is on the government website. Or a solicitor can do it for a cost - but you will still need witnesses and a certificate provider.
Read it slowly and carefully. It is possible to do it without a solicitor, but take your time and dot every i and cross every t. There are a huge amount of decisions your aunt needs to make, how many attorneys, how they make decisions, when they make decisions, whether they overrule medical decisions, what they bases decisions on, what preferences they want decisions based on, etc
I have cancer and recently signed POA over to my sons. It takes around 6 months to be processed, after the application, assuming you fill in the application correctly
Any further questions, please just ask. I will help if I can