Whow. Stop. Do your research again.
(Also see plenty of threads in the UK & Ireland section.)

The Heathrow Terminals are divided in to 3 sites:

The Central Area:
- Terminal 1
- Terminal 2 (under reconstruction)
- Terminal 3
There are NO hotels in the central area.

Terminal 5: (west of the central area)
- Sofitel on site

Terminal 4: (south of the central area)
- Hilton connected to the terminal
- Yotel (japanese style capsule hotel) inside the hotel (landside, accessible to all)


There are loads of other hotels near by. Including many on Bath Road, just north of the airport, running parallel to the runway, which is the main 'hotel strip'.

Are you flying INTO and OUT OF Terminal 1 on both occasions? Or changing terminal?
What time do you define as 'early'? (I.e. when does your flight leave in the morning?)
And how late are you arriving?

Lots of luggage or travelling light? (through checked luggage, etc)
Just yourself or a big party/family group?

All of this affects the advice.

Depending upon time of day, a terminal connected hotel at a different terminal may be more hassle than another hotel off site. (And with the price premium for being terminal connected.)