Does backpacking/travelling constitute ‘living abroad’ for UK tax purposes?

Trying to buy back missing years of NI contributions for my pension. 1. I was backpacking for an extended period and am not sure if this is ‘living abroad’ - I did not work abroad during this time. 2. I also studied languages at uni and during my year abroad I worked abroad - is this ‘working abroad’ if it was an Erasmus internship as part of my university course?