This website has three version that will automatically be displayed depending on which type of device you are accessing it on

It uses the terminology of parent/child to define primary navigation landing pages - parent (top sections) and sub pages as child pages

  1.  Desktop

This will show the navigation pane on the left hand side, as shown below

 If it does not show automatically, or to close it temporarily, click on the box icon just to the left of the search box at the top

 You can also use the Menu drop down at the top

2. Tablet 

When you access the site on a tablet device for the first time, you may be presented with the mobile version which looks like

You need to switch to the desktop version to be able to access the top menus which is done by clicking on the button in the top left corner with 3 lines on it, which will then display

Then click on 'Switch to desktop version' and the display will change to

And you will now be able to use the Menu navigation drop down at the top