I'm planning to book J award flights CDG-LHR-SYD for October next year when seats are released for the date I need.

If I can get seats on BA15 I plan to book an early flight from CDG - probably BA303, arriving at LHR at 07:45. This would mean we could spend the day in London and return to the airport late in the day, ready for BA15 that departs at 21:35.

When we check in at CDG we would check our luggage through to SYD. For hand luggage I usually travel with a camera bag and a laptop bag but would only want to take my camera bag around for the day. Are there lockers or anywhere else, perhaps at the lounge, that I could leave the laptop bag at LHR until I return to the airport?