This used to be really difficult to do. Because of the high level of pull-out forces involved with awnings and, as mentioned elsewhere, because these stresses can mean the fixing can fail and a catastrophic accident take place, we used to have a builder remove the roof tiles to gain us access to the space above the soffit/guttering, and then install timber blocks between the roof joists, and then we could fix our brackets upwards into this, once the roof tiles were replaced.
Now we have chemical fixing methods available and a whole array of amazing brackets that can give us solutions to all the problems we use to have decades ago, YES - you CAN easily have an awning on a bunglaow or single storey extension.
You'll need what we term an 'end-fix' awning - this is one that only has two brackets, both of which are at the extreme ends of the unit. This way we can install 'Bungalow' or 'Gutter' type spreader brackets that mean we gain an extremely strong and stable fixing, but we can also position the awning exactly where we need it - be this out of the way of some outward opening doors, a low soffit and gutter or similar obstruction, or simply allows us to 'spread' the weight and stresses of the installation into the available lower courses of brickwork.
Always get your local awning supplier to check your building before quoting. This should always be without obligation!