If you don't know where on the map the school you want is, click on the button at the far right of the grey bar which looks like four corners of a rectangle. This will open the map full size in a new tab or window.
You can find the school you're looking for on the left hand side. The list is divided up into primary schools, secondary schools, and special schools. You'll need to click the words '... more' to see the full list of primary schools. When you find the school you want, click on it, and it'll be highlighted on the map. You'll also see the red bar appear, with the school's address and contact details.
Click on the button at the top right of the red bar, which looks like an arrow inside a diamond shape. Google Maps will open in a new tab or window. You can then type in an address, and choose whether you want directions for driving, walking, public transport, etc.