Serious replies only? And you want to join the Infantry? If you want a serious reply try asking the person organising the visit!
However, since I have nothing better to do with my lunch break;
No set formula, totally depends on where the Bn are and what they are doing and who's organising/hosting you. It can be a bit dull if half the bn are on leave for example, very exciting if everyones in camp and something interesting is happening. However, they are generally great fun - have an open mind, be enthusiastic and throw yourself into whatever they ask you to do. Usually involves shadowing a junior officer, a few interviews/chats with more senior types, at least one pysical PT session with the guys and dinner/drinks in the mess. You will probably drink a lot, might end up in town with the subbies. If you're luckly you might get some time out on excercise.
My Bn always used to leave PO's with the junior NCO's and Riflemen for a couple of hours as well. A key part of the visit.
Ask whoever's organising for a kit list (ie, you might need a DJ on some visits etc).
Also, it's usually a little different from a Corps visit - because of their size and number of PO's, Corps tend to have bigger centrally organised visits which are a bit more standardized.
Relax have a good time, be yourself and join in but try not to make a total arrse of yourself, it's a two way assessment - you're choosing a family, they are also choosing you.