The Spectrophotometers (Scanning machines, to give them their proper name) in B & Q are not bombproof - they can be a nightmare to calibrate properly... I should know!
With the Valspar range, there are a few that can look Blue/Grey and a few that can look Green/Grey. Summer Grey R206E
https://www.valsparpaint.co.uk/colours/pre-selected-colours/greys/
is one of the most popular shades. If you ask your friendly Paint Pro to give you a piece of White paper, it can help to put the colour cards onto the white background.
The Dulux colour Frosted Steel only comes in the Easy Care Bathroom or Kitchen ranges - the Bathroom is a Soft Sheen finish, and the Kitchen is a Matt, so you could use the Kitchen emulsion without a problem. No-one would have to know.