Hi,
You should get:
(1) Business class check in - at LHR this can be very useful
(2) Lounge access with free drinks and some snacks
(3) On board if it is the Airbus choose the left hand side seats (A-C) as you will have the middle (B) empty and the seats will be wider. It is 2-3 configuration compared to 3-3 in economy
(4) depending on the time of day you will get a hot meal in the Bento box
(5) Hopefully priority luggage tag - sometimes works sometimes does not.
(6) you should be able to get allocated seats in advance
(7) You should get off the aircraft first.
Have a good flight
Regards
TBS