I too remember your orignal post. So glad to hear that your vet is sympathetic and has a heart. So sorry to hear about your cats pneumonia. I hope she makes a full recovery. please let us know. I am surprised that the PDSA would not help you. I would have thought that being on a pension would qualify. I am sure the RSPCA will give preferential rates to pensioners. have you tried them?
When your cat has recovered I would seriously look at ways to prevent this tartar build up again. I had a cat who had this problem. He had to have his teeth cleaned 4 times in his first 6 years. Then the vet recommended LOGIC ENZYMATIC TOOTHPASTE. It will not get rid of existing tartar, but will help prevent tartar building up in the future. I used it on my problem cat and he lived for another 6 years without ever needing his teeth cleaned again. I use it daily on all my cats now and never have any oral hygeine problems with them. It is not a gimmick, as so many pet products are, it works!!!!! It costs less than a fiver from VET UK ( just google them. They are much cheaper than your vet and postage is quick and free. It will be the best fiver you ever spent on your cat. You do not have to brush their teeth lol. You just put a blob of it in her mouth every night. If you are lucky she will lickm it off your finger like mine do. They love it and they think they are getting a treat. i know how tight your finances are and I would not urge you to spend money on this If it did not work. Enough said.