Hey friend,
So by the sound of it you'd be growing in 100% peat moss? Many people will consider this a type of "soiless grow" because usually peat moss doesn't have nutritional value. Firstly I would double check if they have put any white looking tiny rocks in there, perilite/ vermiculite/pumice something like that, if not I'd suggest you mix 1/3 of your pot size of one of those in to help with aeration. Now with the added nutrients, either they have put in nutrients that feed over several months kind of like miracle grow does, but either way you're going to need to have some nutrients ready to use after a few weeks. You'll also want to have a ph tester and something to adjust it with drops etc.
*normally people use peat as an addition to make their own soil or just as a mulch to decompose into the garden and for water retention. Be mindful that it has a pretty low ph so you will definitely have to counteract that, and then just grow similarly to someone using just coco coir.
I'd suggest calling Growmoor if you're able, or email them as they're a garden store in the uk and they might be able to give you a little more specific information. Ask about the blend of nutrients used.👍
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