yes mate...but, in scotland we only have to prove competance (unlike down south where they have part p) to sign off work according to SBSA. but not all councils play by the rules. Edinburgh for instance insist on a nic or select member certs whilst i believe glasgow city council will accept certs providing you have a recognised apprentiship and 17th edition. Each council and even different inspectors have different requirements. I myself have svq level 3, 17th and select inspection and test and i send a copy of these along with certs and calibration cert to highland council and have never had an issue.
yes worth getting 2394 ( 2391 has been recently discontinued replaced by 2394 and 2395) 2394 is initial verification whilst 2395 is periodic. The other option is to do the SELECT quals but be aware there "watered down" versions of C and G and not really recognised outside scotland.