I've done it for myself and wife, download them from the gov website, one for Health and Welfare, other for Finance, so in our case four to complete.
Once you have done one the others become much easier because it's repeating same questions.
Obtain all the necessary signatures and send it off to the Public Guardian's Office, if there is an issue, I.e you have filled something in incorrectly they come back to you and I believe you have one month to correct.
Once sorted they will send back POA and confirm registration so it's impossible not to know if there is an issue with registration.
Personally I wouldn't go anywhere near a solicitor the online info and downloading of forms is a much more cost effective way of doing it.
Meant to say during the process the nominated attorneys are advised they have been selected and have three weeks to decline so everyone is in the loop.
Hope this is of help.