Can I do my own LPA without a solicitor?

Yes. You don't need a solicitor to make a valid LPA in the UK. The Office of the Public Guardian's forms (LP1F for Property and Financial Affairs, LP1H for Health and Welfare) are publicly available and can be filled in by anyone with capacity. What people pay providers for is not the legal authority — it's the help avoiding mistakes that get the form rejected at registration, the plain-English explanations of the more complicated sections, and the Certificate Provider role if you don't have someone to do it. A rejected LPA means waiting another 8–20 weeks while you fix it and resubmit, so the saving from DIY can disappear quickly.