I've had a side and rear extension built (no extra bedrooms), but the council BCO says he wants an electrical certificate before he will sign off the whole job.
Strictly speaking, they only need an electrical certificate for the work done as part of the extension - having the house re-wired was not part of that and so shouldn't stop them issuing a completion certificate for the extension.
I never thought at the start I had to tell the council I was having the old house wiring and fusebox replaced.
Well, again strictly speaking
IF the electrician was a member of a recognised scheme then you didn't have to tell the council - it is sufficient for the electrician to do the work and notify it through their scheme (which is also a
LOT cheaper than you doing it thrugh a notification yourself).
... and a mate of the builder did the wiring 18 months ago
And he should have provided an installation certificate. If he didn't, then he failed to comply with BS7671 and you should report it to Trading Standards, and his scheme if he's a member. Did you employ his directly, or was he sub-contracting for the builder ? If the latter, then your builder is responsible for the sparks failings and you should tell him to get it sorted out !
so it's easier to get a sparks to test and issue a certificate
At this stage, yes - though as previously stated, not a test certificate but an EICR (Electrical Installation Condition Report).
As an aside since I don't think anyone's explained this yet. If you apply for building regs notification for electrical works, some councils (mine did last time I looked) have two different charges - if you can provide a set of test results/an installation certificate that's acceptable to them then there's one charge, if you can't then there's a higher charge. As most BCOs aren't qualified electricians, they will outsource any testing to an electrician.
When the building control rules changed in 2005 there was something of a debate as the BCOs were effectively asking electricians to certify someone else's work - which they are not allowed to do. The compromise was for the electrician to do an EICR (which they can do) which (if done properly) will provide most of the information that would be on an installation certificate. However, the electrician would want paying for this, and BC departments were not allowed to charge for inspections - hence why there were two scales of charges to get around this.
AIUI the rules on charges have now changed, having a quick look, it's now not clear what the charge from my local BC dept would be for (eg) a CU change.