Complex sentence: At 17, he went to Glasgow University to study physics, during which time he appeared in a community workshop (part of theatre company in Glasgow) and then later he went to Caledonian University to study Optometry.
Split into simpler sentences: At 17, he went to Glasgow University to study physics. During which time he appeared in a community workshop (part of theatre company in Glasgow) and then later he went to Caledonian University to study Optometry.