I am interested in your Terminal 5 BA First as well, Gilly/Marshy.
We are off on Tuesday to Terminal 3 First, it will be our second time but am already excited, and have BA First Terminal 5 booked for next June. Did read Dragon Lady's trip report anything is better than the ordinary waiting areas, considering both Firsts are on a 2-4-1 its even better , yes you get the meals selection a month out, and have just received our pre flight concierge services of booking a spa or porter services .
We always travel down the day before coming from Cambridgeshire and will eventually book us into the Soffitel, for the Terminal 5 trip, if you use Lastminute.com its their secret hotel for half the normal price, and you can go through Topcashback.
We are only on a 747 but only three seats are booked at the moment on the way out although seems to be full on the way back, I always book us into 2 and 3 so we get a window view both ways. I am sure you will enjoy whatever seat you are in. Linda