The recipe doesn't make a huge amount and can definitely be doubled ... so I suggest you stick with this quantity first, and then double the recipe later if that is your preference.
These biscuits keep really well in a sealed container for up to three weeks.
RECIPE UPDATE March 2018:
I was in a rush today so I doubled the recipe (follow exactly the same process), and instead of rolling the dough out and cutting with a shape, it was quicker for me to use a tablespoon measure and roll that amount of dough in my hands into a ball (damped your hands every now and then with water to get a smooth finish), place onto the baking tray, and then press with a fork on the top ... similar to what you see in the pics with the leftover dough ... but they were bigger!
To be honest, I actually preferred the biscuits this way ... by doubling the recipe and using a tablespoon measure I got 26 biscuits, I baked them for a total of 18 minutes (10 minutes first, turn tray around and continue for a another 8 minutes) and they were simply perfect xo