Ally
I don't think there is a place big enough in Padstow at the right price to handle all Pests unless some decide to bunk in the same bed
. To get a decent deal and all Pests in the same place, Trevose is probably the best bet. They offer seasonal deals and with golf inclusive. I know its not in town, but nothing is perfect with a large group on a budget around Padstow. Otherwise, its back over to the Tzitzikama Lodge in Rock, but it has no bar which from experience can lead to group dispersion.
The other thing to try is the Metropole. I can see them possibly doing deals in Sept. I had a look round the place in July. I wasn't impressed for the amount of money they want per night.
I also checked out the Treglos. Its quite close to Trevose. The hotel is a bit chintzy, but clean. But to be honest, if you are staying near Trevose one may as well say at Trevose unless you get a cracking group rate.
Its a difficult call to either be in town and likely dispersed or out of town together, but in a captive market situation and likely using taxis. I will say I once stayed at Trevose and it was very good for the money, but we were only there for two nights. One night we went into Padstow.
Ciao