About 45 minutes from Heathrow to hotel on the Piccadilly Line. This is by far the easiest and cheapest way to get into London from Heathrow. There is all sorts of upselling for Heathrow Express, but it’s almost four times more expensive and if you’re staying in the western part of the city you’ll overshoot and need to tube back anyway.
Tickets can be purchased from machines in the Heathrow tube station using cash or credit cards. Note that, at least in my experience, Canadian “contactless” cards — Visa, Mastercard, Interac — do not work on the turnstiles themselves, but can be used to purchase paper tickets.