How are we going to occupy a 7 mth old for that long , i do not know
Check in as early as you can and try and score the bassinet/sky-cot (a cot the flips down from the wall under the movie screen in front of your seats. Then when you have finished take off/feeding, pop her in the cot and hopefully she will sleep.....the noise of the engines will often send them off. Then when she wakes she can sit up in the cot and you can feed her some solids and let her have a play in there: take loads of little toys and books.

(I know what you mean though: I was really worried about this with Charlie when we went to the UK.......he ended up "performing" from the cot to the rest of the plane: it was hilarious!)