Phil,
Fit a narrow band lambda sensor and enable it - Thats my recomendation.
You have done all the high boost stuff and most of the mid range mapping.
Let the ecu adjust the idle and part load fuel automatically and it will
make lambda 1.0 @ idle and whilst cruising.
The second you try to accel or go on boost, the auto lambda adjustments are
disabled and the fuel map you made will be used uncorrected.
You wont notice the driving difference but the fuel used will be less
and it will pass an MOT.