I asked this over in the Transportation forum but thought I'd try here as well: I love the Tube and am very comfortable getting around on it but have never taken it from Heathrow into London. I'm thinking that this time, however, I'll save some pounds and try it out. My plane lands at Terminal 5 at noon on a Sunday. My questions are: 1. Arsenal is playing Man U at home at 4:00 that day. Figuring that I'd be getting on the Tube at LHR somewhere between 12:30-1:00, would that likely be early enough to avoid trains packed with supporters? 2. I have an Oyster PAYG card from a previous trip which I plan to top up with, I don't know, £20. Will that pay for the trip from LHR in to London? In other words, provided I have sufficient funds on my Oyster card, can I use it to pay for that trip (don't need a separate ticket)? I'm also wondering if it would be worth transferring at Acton Town for the District to Ealing Broadway, and then the Central to Lancaster Gate (where my hotel is), or if should just stay on and transfer somewhere in Zone 1, like Holborn. Opinions?
Since your journey is on a Sunday, it's unlikely that fans heading to the match will have much of an impact in terms of train crowding. If it were mid-week and there were lots of office commuters also using the trains it would be a different story. 20 pounds on an Oyster is more than enough to get to from Heathrow to central London.
It is £3 to get from Heathrow to Lancaster Gate (£5 if you travel between 6:30 and 9:30am M-F). I would transfer from Piccadilly to District at Hammersmith - you just walk across the platform. You are looking for the District line to Edgware Road. Transfer to the Central Line at Notting Hill. This would be SO much easier than going to Holburn.
I have already replied to your post on the transportation section. Holborn is a terrible place to change. Notting Hill Gate is not much better - as it was originally two separate stations connected together. As I said before my recommendations are: Train to Paddington and a five minute walk. (You could do Paddington by underground if you wish) Piccadilly line to Hyde Park Corner then the 148 bus.