If you meet the conditions of your firm choice, you have to go there (you've agreed to contractually on UCAS). If you meet the conditions of your insurance choice, but not your firm choice then you have to go to your insurance choice.
However, you could phone up your firm/insurance choice on results day (whichever you get into) and get them to release you into clearing if you want to go somewhere else.
If you get the grades for your first choice on results day then you go there and your insurance choice would have likely given your spot away to someone else.
You don’t get to swap on results day. Even if you miss your firm offer conditions it’s very common for universities to accept applicants with lower grades.
It is possible to swap firm and insurance choices with the agreement of all universities up until July - but if you are struggling to decide then use the time you have now. Visit again, talk to staff and students, write down pros and cons lists, make a decision and then sit on that decision for a month.
You shouldn’t be picking a firm choice on Track until April at the earliest. There’s no advantage to making your choices official early.
I’m currently finalising my decisions for Uni, and I wondered if I put my unconditional offer as my insurance choice ( 2nd choice) and I put my conditional offer as my firm choice ( 1st choice) and I then meet the correct grades for my firm choice, does it mean I automatically have to go to my 1st choice or once I’ve got my results can I then either accept or decline first choice and go for second choice or visa versa ?? If that makes sense 😂💁*♀️