As zero269 said, most Blu-ray players support reading many file formats as plain data. They support it at least from a USB storage device. I never tried out to burn plain data onto a disc and try that, too.
If you want to go the extra step and author a real video disc with menu, the main problem with your current file will be that the audio is in AAC while the Blu-ray specification only supports PCM, AC3 and DTS and that the subtitles (if any) are in a wrong format. Blu-ray has it's very unique subtitle format that is based on pictures instead of text. I think it may also still support the Closed Captions text format which was common on DVDs but I don't know for sure. But it needs to be converted nevertheless.
The video material, when in H.264 (also known as AVC), will be directly compatible if the source has exactly the dimensions 1920×1080 pixels, so then you only need a tool to convert the audio and subtitles and then remux it back together. But if black borders on the video material are missing, those have to be added back, resulting in an extra time-consuming video encoding step.
As for what freeware tools will be the best, I don't know. I think
Handbrake will be a good choice. If it doesn't work for subtitles, there's the special tool
Subtitle Edit that supports exporting to Blu-ray sup format. But then you are still out of any menu and have to create the final blu-ray folder/file structure with some tool and when I tried freeware tools in the past, I didn't find anything feasible.
I finally settled on buying
TMPGEnc Authoring Works 6 which does everything automatic but still allows enough customizability that you can imitate your vision. Keep in mind that it re-encodes the video even for the slightest incompatibility even if 99% of all Blu-ray players would have had no problem with the source video. But therefor it's fully automatic and produces a nice Blu-ray with customizable menu very easily. And if it was encoded once, and you need to change something, just exchange the old input files with the new output files from first build and it will do the really fast remuxing when rebuilding the blu-ray again. If the process of imitating your vision takes longer, it allows saving the current project and returning at a later date.