Back to basics then .
You NEED a mains tester .
Switch the MCB on , is there any voltage at the top terminal ?
Is the MCB properly clamped to the bus bar finger?
Has an RCD tripped ?
Are the cables connected properly at the top of the MCB?
What does this spur actually do ?
If there was voltage at the MCB , why isn't it there at the sockets ?
Theres a break between the MCB and the socket ... I hate plasterers so it must be his fault .
You really need a mains tester .
Edit:
With only a continuity tester , switch off the board , test continuity from bus bar to top of MCB .
At socket connect L to E and test at board between L & E , ten with N etc