This forum was so helpful to me in planning our trip to England. I'm sharing a trip report in case our experience can be helpful to others!
The Basics: My husband and I (both in our 50s, both fairly well-traveled) visited England from Oct 14-27. We flew in to Heathrow, went immediately to Bath for 3 nights, then spent the rest of the time in London.
Transportation: We took the National Express bus/coach from Heathrow to Bath. Our flight was due to arrive just after 7am. This was our first time in England, so didn't know what to expect as far as customs, so I booked us on the 11:30am bus to Bath (32 pounds total for the two of us). I knew we'd have a wait but it felt safer to build in the extra time. I saw some advice about buying a changeable ticket, but it looked like we'd only be charged a 5 pound change fee so I didn't do that. As it turned out, our flight arrived at 6:40am, customs took about 3 seconds, and we went to the National Express counter to see if we could catch an earlier bus. There happened to be a 7:30am coach, so we said yes. Unfortunately, in addition to a 5 pound change fee, we were charged 39 pounds more for "excess fare" or something like that. Basically, it seems like they surge priced us. But we paid it as we just wanted to get on the road. The heater on the bus was broken (it was about 45F and rainy) so not the best start. Though really, it was better than sitting in the arrivals hall at Heathrow for 4 hours. And now that we're home, I looked on the National Express website and it does say that changing a standard fare can result in "excess fare." I do think more than doubling the original cost is a bit obnoxious.
I'd also advance booked train tickets on Great Western Railway for our trip back from Bath to London. I reserved two 2d class seats, booking about a month in advance. On the day of our trip, we boarded and there was someone in our seat. It turns out that no reservations were honored at all on that train because they had reduced the number of cars on the train to 5. Initially we couldn't find seats together but people got off on the first stop and we moved to sit together. Not the end of the world, certainly, and the train ride was comfortable and efficient.
London Underground: based on advice from this forum, we used our credit cards to tap in and out, rather than use the Oyster card. Worked like a charm. We hit the daily cap most days (still waiting to see if we qualified for the weekly cap). Absolutely loved being able to get anywhere we needed to go. We stayed in South Kensington, and the Circle/District and Piccadilly lines got us nearly everywhere, including back to Heathrow on the day of our departure (6:45am on a Sunday morning - no delays and no crowds). My only complaint about the Tube is how hot/humid it can get when crowded.
Accomodation: We stayed at the Hotel Indigo in Bath. Super location, very nice rooms. Would recommend it. In London we stayed at an apartment hotel in South Kensington - Cheval Harrington Court. It was superb. Full kitchen that was actually stocked with bread, eggs, milk, juice and snacks when we got there!! We stocked up on fruit/yogurt/cereal so we wouldn't have to buy breakfast each day and it worked great. Bed was comfortable, shower was fabulous, and the room was clean. Located half a block from South Kensington tube station. Couldn't have been a better spot. I have to say it cost more than we initially planned to spend but I'm glad we stayed there. We both ended up getting sick while in London (either colds/allergies or something) and were grateful to have a comfortable spot. We ended up spending one entire day napping and resting, heating up soup and tea in our kitchen. Also got to know the local chemist fairly well!
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