There are a couple of places in Chinatown, Manchester that have a small selection of Filipino Groceries as well as Wing Yip on Oldham road Manchester which although mainly Chinese has an interesting selection of groceries. We tend to buy our King Prawns, whelks and other seafoods there. By far the best place we have found is JADE'S in Poulton-le-Fylde on the outskirts of Blackpool. The shop although only small carries a far better selection than anywhere we have found in Manchester.
I do not have an address other than it is by the railway station in Poulton. There is limited free on street parking nearby so it is not far to carry the many bags of groceries. Contact cellphone number is 07899 846085 for opening hours etc. There is also a Filipino restaurant nearby.
There is a Filipino restaurant in Ashton under Lyme called Cora's which is near to Rochdale. Hope this is of use.