Hi - a media player on the Pi?
I have 92Gb of mp3 (laboriously copied from my large CD collection) on a USB hard disk connected to a pi 2 running Apache.
Apache hosts a set of php and HTML files, together with the mp3 archive.
One or more pi Zero Ws run a python socket server, which accepts commands from a small web page on either a desktop or a smartphone.
The backend player on this is mplayer, which accepts fully-formed http URLs for each track. The audio output can be connected either via a USB codec, for direct connection to an audio amplifier, or alternatively connected to a Chinese FM transmitter module, which has a USB codec built in, and the broadcast from this can be played on any FM radio or FM Tuner + Amplifier.
The web page is served up by Apache to either a desktop or phone. This web page with jquery etc., has an indexed list of the mp3 archive, neatly sorted into Works, Albums and tracks. It also hosts controls to select a destination server, change volume etc.
Communication sequence is as follows:
1. Choose an album or track on web-page -> executes php file on apache server.
2. Apache-server forwards request to required player socket server (Pi Zero)
3. Player executes play-track, or sequenced play of Album, by fetching files using http from apache server
It is obvious from the above, that one link could be removed if the apache server and player are co-hosted, but using the apache server as a gateway enables many cheap player end-points to be configured.
None of the above uses special proprietory audio hardware. FM transmitter modules, receivers and USB codecs are all available from AliExpress.
I believe that for playing your own mp3/wav files, KODI is a complete overblown waste of space.
BTW Living as I do in Portugal, I also listen to British Radio in a very similar fashion - on an ordinary FM radio, station(s) selected on my android phone.
If sufficient folks are interested, I will post current work on one of my websites.