Thanks Flower Duet, that's what I thought. To summarise my understanding:
Someone based at LHR, who does ALL their training at Cranebank (LHR) will not be paid allowances as there is no need for them. They are not staying overnight anywhere and are not having to purchase meals from hotels, which is what allowances are fundamentally for.
If you are LGW based and do your SEP training at Cranebank, you will be given a hotel and allowances because it is away from base and you will have to in theory purchase your meals at the hotel - just like on a trip.
Sorry to sound pedantic and I'm open to correction but I think it's important to clarify this so people can have an awareness of the financial implications of training, that way they can budget in advance.
Thanks again, Flower Duet.