You can get matches to the FS fan deck on the IPMS Stockholm pages, for instance the references for French colours can be found here: http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_france.htm
The only snag with Fredriksson's charts is they haven't been updated for yonks and a number of new paint ranges have subsequently appeared since these were published, so it's quite possible out of the pot matches might now be available rather than some of the elaborate HU colour mixes (these can also be found in the old Humbrol Colour System booklet if you can find one).
Personally I tend to avoid FS comparisons unless I need FS spec colours. Some matches are approximate because at the end of the day it's a US FS, not a BS, or RAL etc etc.
With respect to Gunze paints, try them! The RAF matches are excellent and the paints spray superbly, whether it's Mr Paint (aqueous acrylic) or Mr Colour (lacquer acrylic). Also a lot of the range is FS referenced (although there are also BS and RAL references). The paint itself is much more readily available than it used to be and there are a number of UK based traders stocking it.