Ok so I'm not sure how anyone else's math turned out, but mine was confusing to say the least.

This recipe doesn't give % of composition, just oz or grams per Liter, but not of finished product, rather TOTAL water going into the recipe, which is... an interesting way to do things.

Also confusing is the syrups (lyle's light syrup and Lyle's Treacle) are done by volume, not weight, further complicating things. After some research and a little rounding, here's what I've landed on for fermentables and their percentage of recipe composition, but first, substitutions due to lack of availability in CA.

I simply cannot find Pale Maris Otter anywhere, so I'm just going with the standard MO on morebeer. Onward!

Cara Gold is also a tricky little bastard to find. And the confusion doubles when you figure out there's Caragold and Cara Gold - from Crisp malting and Chateux malting, respectively. And to complicate matters, they are VASTLY different - Crisp Caragold is 5-8L of color vs Cara Gold which is around 45L.

Given this is a UK brewery, I'm going out on a limb and assuming they're sourcing from Crisp... So Im personally going with carahell at 11L I found Cara 8 from Dingemans on NB, but morebeer is just across the bay from me.

Ok, also, 1tbsp(.5oz - 14.7868ml) of light syrup is 21g, which gives us 1.4202grams per ml of the stuff

I couldn't find much, but I'm going to use the same weight for the treacle.

This is where I've landed for the grain:

Marris Otter    46.8%
Flaked Oats     14.3%
White Wheat     14%
Flaked Wheat    8.5%
Lyles Light     5.8%
CaraHell        5.5% 
Lyles Treacle   2.9%
Torrified Wheat 2.2%

You're on your own for the hop bill.