@moretimeoffguy

As bse118 explained, you’ll have access to the Sakura Lounge, same as all the travellers on JL41, a night flight to London that entitles everyone aboard to use the lounge.

The HND International Terminal Sakura Lounge is notoriously crowded throughout the day but this is not a problem at night time. Most of the people you will find there late at night will be passengers going to London Heathrow, the lounge should be somewhere between 1/3 and 1/2 full.

The full lounge menu should be available, it’s nice enough but not “amazing” in any way. The star food item is the original beef curry which, in Japanese beef curry terms, does stand up for itself. But this isn’t apparent unless one has eaten a lot of Japanese beef curries. There are quite a few dishes to try and anything you enjoy you can get repeat portions of, as many times as you like.

The alcoholic drink section will seem sparse but if you continue to the very end of the lounge, past the changing room and toilets, there will be another drink station at the very end with a wider range of primo choices, you might find some more bar snacks there also, and tea snacks, like individual adult-taste-formulated Kit Kats (less sweet).

If you have the relevant visa and want to enjoy food as pleasure and not as a service, Tokyo is at your doorstep. If you’re nervous about time, the town of Kamata is 2 rail stops away.

Haneda airport itself can be tricky, there are times when all the land side restaurants are all completely full (with even fuller waiting lists) as it attracts day trippers as well as travellers. If you’re leaving on a Holiday or Weekend particularly, make sure you take this into consideration.
Should this happen, remember I mentioned Kamata, it’s just a stop or so away - the tourist information booth near the Keio Rail ticket hall will even give you a map of Kamata if you ask.