If it's the same cost then if they have good teaching it seems like resitting the year is a much better option than being a private candidate.
Was thinking if i become a private candidate I can be a part-time tutor, like once a week (already kinda got my place sorted for that), however, since I've never done that I don't know what to expect or if it's pressurizing?
It all depends why you failed. If you failed cos you just don't know any content, then retake y13. If you failed for any other reason and pretty much get most of the content be a private candidate.