Ok so problems seem to be sorted. This is what happened. I checked connections and fusebox all seemed ok, just tightened a bit anyway. No change, MCSF still up. Went to SYSB batteries they tested my battery as predicted here it was knackered, down to just over half the original power output. Bought a new battery, fitted it. No change still vastly reduced power and MCSF warning.
Anyway I decided to call the AA as i have roadside and parts cover (bit annoying could probably have got free battery, oh well). They read the codes and seemed to have a fault code relating to the Turbo circuitry and pressure sensor.
He said not much he could do, but did a battery reset via his gizmo and reset the fault code and hey presto power back and no warning. Seems to have done the trick.
Do you guys think the turbo faults may just have been symptomatic of the the failing battery and the comp was just protecting the turbo or is something more sinister at play?
Anyway thanks for the help guys.