You say your not a Electrical Trainee and have done 2391 so my question is what the hell are you doing energizing a replacement consumer unit when clearly you have not undertaken any testing! Sorry but clearly you should go back to college!
With regards to no time to test prior I always always book a 5 minuet slot in at the end of a day prior to starting the replacement CU usually on way home from a job to do 2 IR Tests!
1. IR - LE
2. IR - NE
This takes about 5 minuets to do and will never put you into this situation where you have a not tested CU which you have energized and "TRIP"
so you telling me you learnt everything in college? i think i know the answer to that mate