Go to moneysavingexpert and/or moneysupermarket. Lot of info on there. But you only tend to insure against repayments of a loan. Usually mortgages (MPPI) PPI was linked more to loans and cards. MPPI usually comes in form of ASU, or accident/sickness/unemployment
Similar but you can either have it as standalone insurance or along side accident and accident. Most insurers offer it but the terms and conditions are a nightmare, especially when it comes to waiting periods before you can claim etc. Set one up for a client today through Legal and General, worked out at £24 a month for £1000 cover. A lot depends on your job and sector, (the more likely you'll be made redundant, the higher the premium).
I've got mine through Allianz. £22 per month. Previously I had mortgage cover which was £5 per month and gave £400 worth of cover. It was a God send.