Looking for very specific screw - 3x4mm?

lets look at the images first, i guess:

https://imgur.com/a/RQargXf

so this is the door going out to the garden. the door latch (or whatever its called, the thing that goes in as you push the handle down) goes in the door frame, and the part that actually catches the latch is movable for whatever reason. its held in place by 2 small screws, the upper one missing in the image obviously, which are quite done as you can probably tell by the image. which makes it difficult to tighten them.

second image is the missing screw from the top.

the thread itself is 4mm in length, the whole screw is like 8mm or so. i believe screw length is only the thread, am i correct? the diameter is 3mm, without the thread.

where can i get these screws? would prefer if i dont have to buy a pack of 20 or so if you know what i mean. what shop would sell these?

i'm living in the cork city/midleton area.