I've found Slingsby to be very helpful. John Pool is the man to talk to though I think he's away just now. Switchboard is 01751 432474.
As far as getting signed off is concerned, I don't know but I'm told it involves sending your engineers to get trained by Slingsby or having them come down and sign off your work for a while.
Your friend could also talk to Stapleford - they're going through the process.