We visited in year 5 and year 6 (when the open days were in Autumn), so you wouldn't be alone visiting when your DD was in year 4. It's worth visiting all schools you are interested in a couple of times.
While it isn't something to mention this time, next time you go around in year 5 make sure that DD is aware that she will be taking the exam in one of the classrooms. Doing this help my DD visualise the experience beforehand.
I'm sure you will have looked at the threads in here about Kendrick open days, but to repeat just in case
It will be extremely busy. The corridors get quite crowded. Warn your DD beforehand, especially if crowds are an issue. A normal school day isn't like that so don't be put off.
The head can seem quite scary and stern during her talks. She certainly put me off when I heard her. She isn't like that generally and is lovely. The girls all seem to like her and she is very approachable.
There's no parking at the school. Don't think about parking close by illegally and think you'll get away with it in the evenings. Traffic wardens will likely be out and about until quite late. Queens road and oracle car parks are best and give you a chance to see what the walk to school is like.
My DD will be in the textiles room.