Yes you can, but you need to use StoreFloor. Most new houses have truss roofs and the British Standard says that the joists must be able to carry a permanent load of at least 25kg per square metre (e.g. for storage) plus a temporary load of 180kg (assumed to be one person walking around). Every new house has to be built at least to this minimum legal standard, though many can in fact accommodate much more storage.
Despite the joists being strong enough, many new house builders recommend that you don’t board a loft. This is because the traditional method to raise the deck (using extra wooden joists) is very heavy and, since 2013, contravenes Building Regulations in the UK as the wood allows heat to escape through the insulation. But StoreFloor is OK as it is very light and does not suffer the heat loss problem like wood does.
Brand new houses are actually one of the biggest markets for StoreFloor, with thousands of happy customers.