I need help

[Procyanic 0]

Hello, I’ve already tried to look everywhere so I’m asking here as a last resort. My Ultimaker bed plate screws fell out during a print and one I haven’t been able to find does anyone know where I’d be able to find a screw like this  I live in the uk if this is useful but is this a standardised screw and what is it called. 
thank you very much

[gr5 2,072]

apparently some call it a "knurled head thumb nut".  It's an M3 thread like this one but I think taller:

https://www.mcmaster.com/90368A150/