BA to LIS goes from Terminal 3. You are guaranteed a bus gate. The aircraft would either be a 757 or A320. You'll get free drinks on BA but only nibbles to eat. TAP gives a sandwich IIRC.

Lounges - the BA F lounge in T3 is lovely, up to T5 standard, and has a great selection of plonk. Free-pour JW Blue is the highlight (for me at least).

*A lounges - I think you would have to use the London Lounge but not really sure.