Most universities will organise open days during the Autumn term. Usually these are staggered with departments inviting potential students on different days. Dates of the open days will be advertised on the university’s website. Most will expect you to book a place at one of the open days and it will be a case of first come, first served.
The graphic here shows the feedback from potential students who attended an open day at the University fo West London.
Some university departments will want to interview students and interview days will sometimes double up as open days.
It is for you and your son or daughter to decide whether they will go alone or whether you will go with them. Both options are fine. Most universities expect a large number of parents and cater accordingly. Typically, potential students will be shown around in groups and may participate in a range of activities and presentations. You will usually find there is a separate presentation or exhibition for parents while this is happening. However, each department will vary and you need to check all this with the university directly.
Make a list with your son or daughter of the things you need to find out at an open day and compare it with these suggestions.