Reporting back:
Re-Checked every boost/vacuum line with soapy water - No leaks.
Removed intercooler, undid, redid and tightened each connection between turbo and throttle body (turbo connection, y-piece connection, intercooler connection,
BOV connection, throttle body connection etc...) - No leaks.
Checked
BOV with throttle-body cleaner - No leaks.
Removed boost solenoid from car, re-cleaned it, checked air flow (no air flow possible unless current is applied, and solenoid opens).
Checked that the boost line olive/pill is there, waiting for car to cool down to test air flow through it.
If the olive/pill checks out, can I rightly assume that my next option should be to replace my actuator? Can I also assume that one of the ones bought in last month's group buys would be the leading contender (obviously the one for the VF35).