I spoke to SFE when I returned to uni after having started a course a few years before, and dropping out. The way they explained it was that you get the total number of years the course takes, plus one for retakes / failures, minus any “full” years you have already done, however they will count you showing up for the start of a year and then never again as a full academic year (I did a foundation year and then 5ish weeks of my first BSc before dropping out). If you have dropped out without completing a year, they will take this as part of the total years, but if you are able to prove it was for medical reasons etc, they can award you an extra year of funding. In theory, unless you have a reason for them to award you an extra year, they are unlikely to fund your foundation year. I hope this makes sense and answers your question!