looks like there was more than one issue affecting my suspension.
Pump overhauled, new seals and cylinder so suspension raises from access to standard in less than 10 seconds.
Still feels a little lopsided, and this is confirmed by Nanocom with front right being -5 tot target and front left +5 to target.
I now also have an error code front left height sensor out of range (which I can't delete). So I assume I need a new sensor on the front left before I do any more trouble shooting.
Suspension goes up and down fine despite the error code
I assume I should avoid the cheap £30 ebay height sensors