Roly,
I use - Wood screws, Slotted round head, Brass, #4
I get them online from here -
https://www.boltdepot.com/
I do not know if they ship to that side of the pond or not, however you might wish to check on Ebay. Might be able to find them a bit closer. I purchase larger quantities. When I was first starting to use them I was getting them from my local big box hardware stores your equivalent should carry them as well. Hope that answers your questions Roly.
DW