In most schools i have seen, attending pre-school nursery is not a criterion and doesn’t not affect your chances of getting a place. You need to see if you can appeal against one of admissions criteria published in their policy
The appeals process needs to be in relation to a schools oversubscription admissions criteria- if attendance at an onsite preschool is part of that criteria that’s a good place to start. If it’s not mentioned though and there aren’t grounds that the other admission criteria were unfairly or incorrectly applied, then an appeal is unlikely to be successful. Usually it’s done on LAC, EHCP, siblings, distance from school, and sometimes then factors such as religion if a faith school etc. if you didn’t meet those criteria when ranked, you don’t typically have grounds to appeal. Your best bet instead could be to make sure you are on the waiting list, should any offers be declined and reallocated.