Bidet blues (UK 1/2 BSP ? EU 3/8 ?)

Bidet kit fitting gone wrong.
Ordered wrong Tee adapter size with kit from TEMU (kit price : £20 ?)
my choice was :
EU 3/8 BSP
USA 1/2 BSP
ASIA 3/4 ?
I chose 3/8. UK seems to be usually 1/2
it seems BSP (British Standard Pipe) inches aren't the same as Imperial inches.
imho we should all have bidets.