First on NRT to LHR
 

BA6 is a 789 so it can have max 8 seats in the first cabin. If in your flight 4 is already gone I can't really see any chance that avios redemption will became available later. BA is already happy with half fo the first cabin is full, it doesn't want any more avios redemption on this flight. It is more likely they will sell a few more first class seat on cash. Check Experflyer is there any A class availability? That could indicate a few things.

Not sure you have the paid version or the free version. I think you need the paid one to check Flight Availability. If you don't want to post here the exact dates just DM me and will send you back. Also don't forget BA not always releasing F seats for avios. They only promised CW and Y.

So current load is F4 A1 J9 C9 D9 R9 I9 W9 E9 T9 Y9 B9H9 K9 M9 L9 V9 S9 N9 Q9 O9 G0 and no seats assigned as yet. This indicates they already sold 4 ticket (can be cash only or avios or mixture) Ba very rarely oversell first class. So they are willing only to sell 1 more A ticket or 4 more F. Keep on eye but unlikely they will release avios if the load stays like this or they sell more ticket. However last minute it is possible to release some avios seats but hard to say it will happen or not.

One more info. if you could change your flight to BA8 on the same day. (it will leave HND different airport) it has 2 F avios available. Its a 777 so not sure which one I choose on this long flight.

Just to be clear, the EF info you show here is current availability, not current load.

I'd consider the HND flight. Once you factor in the painful travel time to NRT the difference is less than it seems.

Hi,

Depending on where you are in tokyo for your final night, you can get to Haneda from as little as around 20mins ( I took the Keikyu line to HND) or from Hamamatsucho take the Monorail ( the Limosine bus might be another option). To Narita it can depend on where you are starting from, the Narita express from Tokyo station taking around 55mins and the Skyliner from Ueno station about 45mins. I don't know if you have been to tokyo before but getting around some of the stations with luggage can be a bit of an effort ( esp transferring) with the Limosine bus from your hotel being very convenient

The HND lounges are very good ( the JAL F and the Cathay F/J lounge) but I did like the variety of lounges at NRT ( the 2 JAL F lounges, the AA lounge and the QF lounge). I was slightly disappointed with the Cathay NRT lounge ( very busy in the morning with a number of CX flights and the food/drink selection did not seem as good as the other lounges)

Whilst HND is an early flight ( 0945 in Feb IIRC) with checkin opening about 7am if you get there at 7am you will avoid most/all of the rush hour on the trains. It is a long day flight so it is an excellent opportunity to enjoy F ( from HND, on a clear day you will see tokyo then hopefully Mt Fuji ( LHS is probably best).
I would certainly consider HND in F ( as F even in a 777 would beat CW in a 787)

Regards

TBS

Depending on where in Tokyo you are (e.g. Ueno), it can be quicker to get to NRT.

These are excellent points. HND is a nicer F experience with the JAL lounge (and you can also visit the lovely CX business lounge).