Its not a prerequisite to use a solicitor. It's easy to do online yourself, you can save the document and go back to it later, but you will still have to print it out and have it signed in the correct order. There are good guidance notes on the site but if you feel overwhelmed, ask organisations like Age UK or the Carers Centre to help you - they do it for free. This way you only need the registration fees of £110 each (do both of them please), and even they can reduce to half or nothing depending on the donor's financial circumstances.
If both of you want to be attorneys, make sure you understand the difference between jointly and jointly & severally, and try to find a friend of the donor to act as certificate provider - much easier than asking a professional. Best to keep the LPA simple and don't put additional conditions into it - then it's simply a case of filling in the details of the people involved - donor, attorney(s), certificate provider, witness and persons to be told, plus get the signatures in the right order.
Then send it off to be registered straight away with the correct payment (or proof why no payment required) as registration can take many weeks to be processed. Afterwards it's best to get a few certified copies made by a solicitor because you never ever give the original out of your hand ever!