What Phonics system and reading scheme are they using? How do they approach Numeracy? What are the schools strengths in art & crafts, music, PE & games, outdoor activities, nature and the environment.
Playtime, snack, lunchtime arrangements. Do the displays look attractive. If you can, see the hall, resources area, computer suite, do classrooms have interactive whiteboards (and if they do there need to be good window blinds, otherwise the sun shines in and the poor kids can't see anything.) And try to visit the toilets (don't be shy, if this is your first visit you need things to compare with when you visit other schools.)
What do they have in the way of sand and water play, 'home corner', or similar for the youngest ones. Do they have bikes and ride-ons for outdoor play, climbing frame etc.
How do they help children who cry or are unhappy. Ask about safeguarding policy and procedures. How do they handle bullying (in all it's forms).
Evening isn't really the best time to visit, as you need to feel the 'ethos' of a school, and how children and adults interact, so if it looks OK, try to get another visit during a school day. Have a look at their website and latest Ofsted reports before you go.
Good Luck.
PS: I'm a retired male TA, worked twenty years in Primary schools.