Enough time ?

Is it ONE ticket, that you are looking at?

I believe it will be. One way ticket for now, Pullman/Seattle/LHR/Faro

Looks like you will be on BA 48 from Seattle to LHR. You will arrive at T5 and according to information I found, your flight to Faro will also depart from T5.

https://www.britishairways.com/en-us/information/airport-information/which-london-airport-terminal

However, all passengers arriving at Heathrow rom an airport outside the UK will under go another security check if transferring to another flight, even in the same terminal. T5 actually has 3 separate buildings, connected by an underground plane. That Seattle flight generally uses a 5C gate, but in any case when you deplane you just follow the purple “ flight connections” signs—- the ones for staying in T5. They will lead you to the train you take to T5A ( assuming you started in 5C or B). You will pass through the security screening area in 5A. You scan your boarding pass to enter the area—-watch other passengers to see how they do this. And make sure your liquids are all in the separate bag, which you remove from your luggage. Laptops and tablets come out too.

After this you will be in the departures area. Find a board and check for your next gate to be posted. Head there as soon as it appears on the board.

Two hours is plenty of time, even if your Seattle flight arrives a bit late. But you do not want to dawdle and shop along the way. Our experience with BA48, which we have taken at least 10 times, is that it “usually” departs pretty close to the scheduled time, but often has to circle before landing, or wait for a gate.

Wow! Great information.
Thank you so much, out of all flights listed this is the one I wanted most but was very hesitant.
I think I will book this now and work on the flight home. We will drive up to Lisbon and fly out of there.
Again Thanks

A T5 to T5 connection will take about an hour. If you need to go to another terminal then you’d need about 1.5 hours. You will need to pass through security again, but since you’re just passing through, then you get to skip immigration.

I am going to hope for no delays as it’s a little closer than I was wanting, but have it booked.
Worse case we can stay a night and enjoy a quick visit!
Thanks