Hi CA
Welcome to the forum.
You might want to have a look at the following FAQ which explains where everything is;
www.benefitsandwork.co.uk/guides-for-claimants/faq/forum.
If you are in receipt of IR ESA then you should have received a letter asking you to apply for UC.
You are correct, IR ESA is being phased out and claimants are being sent a letter asking them to apply for UC.
You need to seek specialist advice from your local Welfare Rights Organisation:
advicelocal.uk where they can take all your circumstances into consideration when giving you advice.
Gary