It's not an interview. They take your kid into another room and watch them play, interact with the other kids etc. From memory they ask your kid to write their name, or perhaps that was the second round. It was very relaxed. My daughter had fun.
My daughter did the 4+ last year for reception 2018. She had a great time on both Assessment days. She was not forthcoming with information though, all I know is that they read we're going on a bear hunt and she did something with building blocks....and played. I didn't prep her at all just told her to go along and have fun, which she did.
My DD did not do WHS assessment, but based on my experience with 3 schools, there could be a mix of things done on the assessment day(s) - - Teachers read a story and follow up with some questions ,the key is not the right answer but the ability to sit still through the story and raise hands etc. to assess if the child is ready for classroom based teaching. - Puzzles or lego or games or match pairs type of games focused on problem solving. - Frog Jumps / skip / throw or catch a ball to assess gross motor skills. Make sure she is dressed in comfortable clothing and don't be tempted to put in the best hair accessories - Coloring or drawing or tracing or peg boards or beading or cutting on a line using scissors to assess the fine motor skills - Some schools also arrange some free form singing / dancing party to ease in the kids - Reading or writing ability is not essential , however depending on the child's interest , they may ask to read simple words like cat, pig, hat etc. or to write their own name or find their name card from a mix of cards.
Whilst the kids are doing any of these above activities, the teachers are observing them for social skills e.g. are they sharing materials with other children etc. There may be a 1-1 interview in some schools, this is very informal and the teachers will have a casual chat with your child about their birthday party , Xmas or recent holiday etc. My DD was extremely shy at 4 and I was worried that she would not utter a word, but the teacher said she was surprisingly very chatty, so the teachers are good at the getting the kids talking.
If your DD has attended nursery / preschool settings, she should be able to do many of the above mentioned things. Just practice them gently over the coming months, the school can easily find out heavily prepped kids. The whole process is very relaxed and the kids come out all smiling with stickers / cookies. Just let your daughter know a couple of days in advance that you are going to visit a school and there is a play day happening there. Most imp, relax on the day and try not to pass on your nervousness to your DD. Good Luck !