the colours called out fo hms belfast are rn01(ap507a), rn03 (ap507c), rn07 (b6), rn12 (b5), and antifouling red. white ensign do these but they are enamels. is there an alternative in acrylic that is close.enough.
Tamiya has introduced a couple RN colors in their line up, but I do not know what those are in comparison to those codes that you posted. Also Model Master is supposed to be bringing out some new naval colors including RN shades in their Acryl line.
Badger Airbrush has a line of naval acrylics
cant find a supplier in England for the badger paints 
xtracryllic seem to have a good range. maybe ill try them .