....as I would be flying on my instructor's licence still.
It's time this ridiculous misconception was stamped out. A student is never "flying on his instructor's licence"; he is flying under the terms of the ANO (Article 50(2)) and the EASA Aircrew Regulation that permit a person to act as PIC of an aircraft without holding a valid licence if under training. Nothing that a solo student might do, up to and including a blatant breach of the regulations, will have any effect on the instructor's licence.