There are plenty of hotels located in the vicinity London Heathrow airport with the vast majority of the international hotel chains being represented here. Many of the hotels are located on Bath Road, a large road north of the airport which runs parallel to the northern runway, and which is not within walking distance from any of the four terminals.
If you look at the webpage of your Heathrow airport hotel on how to get there they will most likely tell you to take the Hoppa bus to get from the terminal to the hotel, and then of course the Hoppa bus back again the next day. There are several Hoppa routes and they cover all the airport terminals and all the airport hotels in and around Heathrow airport.
However there is just one issue, these buses are not free, they are in fact rather pricey. A single ticket for a Hoppa journey is 5 GBP, a return ticket is 9 GBP.
However there is another way to get to your hotel, and which will save you the 9 GBP so you can use them on something else.
The local buses serving Heathrow airport are in fact completely free as long as you travel within the Heathrow area. But this area is vast and covers not just the terminals but most roads around the airport where there are airport hotels and various office buildings with some kind of connection to the airport operations. However if you want to travel further afield on any of these buses (the buses are not just for intra-airport travels) then you will of course need to buy a ticket.
Just keep in mind that in contrast to using the Hoppa bus, which will stop right outside the terminals and later right outside the hotel entrances, the local buses will not. If you arrive at terminal 2 or 3 you will need to make your way to the ‘Central Bus Station’ (clearly signposted) where you will find the bus stops for the local buses. But these buses usually run fairly frequently.
And when you are approaching the hotel there will not be a bus stop called Hilton, Radisson or Sheraton so you will need to have an idea when to get off. And the bus stop will most likely not be right outside the hotel entrance, instead there will be a shared bus stop for several different hotels and office buildings. But in the vast majority of cases there will be no more than 2 or 3 minutes to walk from the bus stop to the entrance.
And you do not need a ticket, just board the bus. There will not be any questions.
The timetables for these buses can be found on the Heathrow airport webpage or on the Transport for London webpage.