Hi Elaine,
You cannot take out an EPA or one of the new types of Lasting POA which come in on Monday October 1st, unless your dad is capable of understanding what he is signing for.
If he is, then you have just one day to get one of the old-style EPAs drawn up, which takes no time at all, and doesn't cost anything. I'm no good at weblinks, but google Enduring Power of Attorney, or Court of Protection, and you will be able to download the 4-page form to fill in.
The present EPA only allows you to deal with financial matters, which I suppose an invoice is, not decisions about medical treatment etc. But at least its better than nothing.
You will need to decide who is going to be the attorney (or attorneys - more than one is advisable in case of illness etc. of a single attorney as you cannot add new ones later so you will need to print two copies of page 4 I think), and as well as your dad signing the form, so must the attorneys. All signatures need to be witnessed, better not by a direct relative - get the next door neighbours in!
Once it is done, provided that is tomorrow, many organisations will accept it as giving power to deal with dad's financial affairs, with no further hassle (though they may want to see a copy). However, some require the POA to be "Certified", which means going to a solicitor and getting them to sign each page, and then getting photocopies to send to the organisation who wants it. Some require it to be "Registered", which in fact you have to do if you think the "donor" (your dad) is starting to be incapable of dealing with his own financial affairs. Registration involves payment of £120, notifying your dad and all attorneys (via another form which you can download from the Court of Protection), and sending off the original EPA to them - and waiting for up to 35 days - though the Court lost mine and it took 3 weeks for them to find it!!!
The new POAs give wider powers to attorneys (but can be reduced by the donor), cost a lot more to set up (£200 I think), are 25 pages long, and much more complex.
I can see you might have a busy Sunday ahead!
But I can't see why the travel company need all this. Surely you don't need to tell them or your dad anything about Alzheimers, just a message from you dad saying, Yes I am Elaine's dad, I'm not very good at understand these things, and it would be easier for you to speak to Elaine.
Hope this helps.
Margaret