If you are certain that the entire movie is contained in that one m2ts file this isn’t hard at all. Might look at the movie with BDInfo to make sure.
Assuming it is in the one file, TsMuxer can take the m2ts file and output as a complete blu ray disk. Import the m2ts file into TsMuxer, deselect (uncheck) the parts you don’t want, like foreign language tracks, or redundant audio tracks, click on Create Blu-Ray disk in the Output section, set an output folder on your hard drive and hit Start Muxing to begin the process.
You’ll need ImgBurn to do the actual burning to the BD-R disk. Import the new files into ImgBurn, set it to use UDF 2.5, make a label, set your burning speed and click on the disk icon to start burning.
BDInfo, tsMuxeR and ImgBurn are all free to download and use.