Can anyone help? This is my itinerary:

DEL-LHR (arriving 6am ish) and later that day, LHR-MEX (leaving 2pm)

Am I correct in thinking that as a GCH travelling in CW on both sectors (but on different PNRs) I can check in my hold luggage for the MEX sector upstairs at departures as soon as I clear customs inbound from DEL and I'm not restricted by some sort of 2 hour rule?

I just need a few hours in central London that day before heading onward to MEX and would like to only keep my hand luggage with me...

?
Thanks!
HL