Is this yeast classed as instant yeast?
No, that is just normal dried yeast. Allinson do an instant yeast (they call it Easy Bake yeast) that comes in a green container.

You can still use your dried yeast though. Use double the amount, and instead of adding it to the flour, add it to the milk (which should be warmed very gently first - not hot, just 'finger warm'). Let it sit for 5 minutes and get bubbly, then proceed as normal.