All I did was ring my bank, they sent 1 (4 page iirc) form out and 8 weeks later I had all my money back + 7% interest and an additional 30days interest to cover the potential time it could take to go into my account (4 days).
Don't go to a claims company it's simple to do. Just make sure you load the answer in your favour and you will be asked about sick pay etc
I get 12 months but they never checked so I could have lied.
I believe PPI is the same type of product regardless of what it is against.
My mortgage company were all but screwed as they said I had to have it or I couldn't have the mortgage. I also had the sick pay in my favour, the fact I still had PPI at the time of the claim and I didn't take out critical illness cover as that was not optional (yes I now know PPI is optional but I was told it wasn't).
I believe PPI has to miss sold or if like I you have good sick pay cover then it may not be needed.
I think if you have claimed on PPI you are less likely to be successful but that is just a guess and not a educated answer.
Give em a ring mate I think you will be surprised how easy it is.
I think it took me 15mins to fill out the form, which was bog standard questions along with please tell us why you think you have a claim question.
Go to the ombudsman web site and download the 11 page doc. so simple to do yourself. Every credit/mortgage site have a PPI claim link on their web site to get the address from (just search PPi claim on their site, also usually down the bottom of the home pages). Send it recorded too.