Most unis don’t mind you switching the once, maybe again depending on circumstance. If you are on student finance, that stops after 4 years worth of study, so you’ve already gone through half of that. If you were to switch again, and your uni let you (I don’t think they would be too happy since it is extra work for them and for you. They might ask you to make a decision and stick to it. For gap years, some uni may still need you to pay for the year to hold your place essentially. So again, that’ll make things harder for you financially at least (potentially). And it’s not a year off you took, you began a new degree programme so they might have a problem with it unlike if someone had just taken a year off and decided they wanted to do something different when they went back