John, if one of the other Sainsbury credit card users was developing something along those lines, it would be possible that it would be easier to parse the HTML rather than the PDF. I will say that either way, it would be rather specific to a particular card, so the number of customers of that utility would be limited. Instead you would want somebody who would be making it somewhat for personal use, and that somebody could potentially let you ride along. Something made to parse one PDF is not likely to be able to parse a PDF from a different provider.
For fun, you could try copying the PDF statement with Ctrl+A and paste into an empty spreadsheet.
Then on the website, copy some stuff, and paste that into an empty spreadsheet. Which makes more sense in the spreadsheet initially? I am not suggesting that you carry that farther. This would just be some background info that you might find of interest.
I am just thinking about how I would do it... I am not going to do it however. I am fortunate that one of my credit cards actually provides a server that delivers OFX/QFX to software I use, and the other lets me download OFX/QFX files. If those were not available, I would be thinking more about actually doing something.
I will also say that it would be easer to produce QIF than OFX if somebody was doing the parsing. OFX is much better for broker accounts, but QIF files are adequate for credit cards.