you can get a front set for about £10 at the scrappy as said^
new nipples are like £3 each from vauxhall
nippel and cap part numbers are in this thread
https://z22se.co.uk/threads/caliper-reconditioning-parts-list.23251/#post-1201479
do you have any EZ-outs ? give it a soak with penetrating fluid and then screw the stub out no need to drill a hole in it 🙂 you would still need a new or replacement nipple
and heres my vid of reconditioning a caliper with big red seal kit so if you do buy a set from the scrappy you can make them like new 🙂
https://www.youtube.com/watch?v=wWjwxYT_Xho