After N2 is K1 and childcare hours is the same. Many pri schs now have their own student care (though priority will be given to families on some kind of financial aid) but if can't get, there's always other student care centres outside. Best to find one near your house. Easier for u to fetch. If your child's sch is quite far frm the student care centre, u'll need to pay the student care bus transport fees too.
the childcare centres opening hours should remain the same regardless of which grade the children are in. for primary school, I don't have much advice since my kid is still young hehe, but I'd recommend you think of alternative care in advance, eg your parents or a helper to lend an extra hand
for PCF, kids auto promote to PCF kindergarten or MOE Kindergarten if center is small. if it's MOE Kindergarten, there will be Kcare after/before the 4hrs class. as for Primary, you may choose to put your child to nearby student care center after school.
There are students care in the primary school or centres outside, eg Happinest (some even fetch your kid from school)
if not grandparents, student care