Your usage of 121.5 was entirely justified and reasonable.
I agree, BUT you have to see this in a UK perpective.
In the UK there's a dedicated organization (D&D) monitoring 121.5 24/7 with sufficient antennas to have a good chance of reception, even at low level, over the whole of the UK. In addition to this, D&D actively encourages students to request these training fixes a few times during their PPL training to get used to the services offered by D&D. Plus it's good practice for D&D.
This is not so in most of the rest of the world. Over there, there is usually no dedicated organization monitoring 121.5, but it's a joint responsibility by aircraft (per company ops) and local ATC units. In those places, 121.5 is exclusively used for emergencies and anything on that frequency that's not considered an emergency is frowned upon. In part because the volume settings of the various radios may be set so that anything on 121.5 is louder than the rest, so it may cut across other traffic.
So asking for a training fix on 121.5 *in the UK* is entirely justified and reasonable, but don't expect the same welcome in most of the rest of the world.