Glyn,
Melodic Minor is essentially 2 scales in one. Ascending it is almost identical to the major scale except it has a b3. C Melodic Minor is C, D, Eb, F, G, A, B. Descending it has a 6b and 7b in addition to the b3. C, D, Eb, F, G, Ab, Bb.
Typically I would think of using a Melodic Minor scale over an altered dominent 7th chord rather than over a minor chord. In this example below, consider "A Blues" putting and F Melodic Minor Scale over the 5th (E) This YouTube Video demonstration uses the Jazz Melodic Minor Scale.
https://www.youtube.com/watch?v=CZQ5NeHdrrM F, G, Ab, Bb, C, D, E. So over the E7 Chord this melodic minor scale introduces the b9, #9, 3rd, 5b, #5, 7th and root. If you played the descending scale with the b6 and b7 you would be playing the 6th (C#) rather than the #5 (C) and the Maj7 (Eb) rather than the root (E) on the way back down. Hearing how to use these scales is really best demonstrated with audio to understand how they interact with the underlying chord. Once you get them in your ears you will find applications for them.
You can really go crazy studying scales, modes, etc.. A very simple way to break down the whole paragraph above is to say, play the melodic minor scale 1/2 step above the 5th. You can do similar things with Diminished scales or Arpeggios to create movement or transitions. Consider an Ab diminished over a Dm7 to G7 on the way to Cmaj7.
Below is a nice example of some Melodic Minor Pentatonic uses.
Rick Beato Melodic Minor Pentatonic Scales
https://www.youtube.com/watch?v=LZpz2gpSdSM Hope you find something useful here.
Regards