that would be the 0.05"
Try a local DIY store, or ironmongers if you have one near or the best place, a team mates kitbag.
Wickes have a set for about £10, its awesome, both metric and imperial 3/8" -0.25" and 10mm - 0.7mm haven't found anything the wont strrip yet.
edit - they are loctited in too if you didn't know so heat it up with hot water first or it will take you an age and probably strip the head of the screw.