I'm afraid that seems about right. If you're on duty overnight 'permanently' then duty food should be provided in that period, be it packed lunch or otherwise. We did irregular night standbys with no food provided as it wasnt unreasonable to have dinner (bfast) then work then breakfast (diiner?) then rest (remember few of us get lunch at public expense or as part of DMR as its been PAYD for ages) Also, if you are off duty you cant miss a meal due to service reasons therefore no MMA....
HOWEVER, this isn't for you to sort, simply ask of spt wg, "where do we eat"?