We plan to take a train from York to London on a Tuesday afternoon. What is the best time to arrive in London to avoid chaos on the Tube upon arrival? Our hotel is on the Piccadilly Line, westbound. Should we purchase tickets in advance? What station does the train arrive into?
Any time after 9AM and before 3PM, your train will land at Kings Cross Station. Have a great trip.
Kings Cross is on the Piccadilly Line. Definitely book tickets in advance (up to 12 weeks before the date of travel for the lowest prices) on http://www.eastcoast.co.uk/ . 'Advance' fares can be really cheap, but are only valid on the specific train they are booked for and cannot be refunded. Cheapest fares sell out quickest, unsurprisingly. If you miss that specific train then you have to pay the full single walk-up fare (which can be very expensive), together with a penalty if you board a train without a valid ticket. If you can't be sure of catching a particular train then you will need an 'Off-peak tariff', not an 'Advance'.
I'd say arrive before 5pm or after 8pm. I've done that trip a few times and usually grab dinner in York and then the train. I check the time of the last train and then go for the next-to-last one. York-London trains are frequent throughout the day. Buying in advance and booking seats (if offered) saves money and removes the risk of not finding seats on a busy train. (Edit: The York station is an easy walk from anywhere in the town center. Equally short cab ride, too, but walking might get you there quicker if there's traffic.)