Income tax & NIC on bonus shares and leaving allowances - non resident

I left Scotland on 1 April 2023 after i was a tax resident for 6 years straight. I moved intercompany to the Netherlands. I have a sizeable amount still showing as income in tax year 2023-2024: 1) my employer paid me some allowances in April 2023 related to my move, and 2) I am part of a global bonus share scheme. These shares mature over a 3-year period. As they are awarded during my time in the Scotland, they also mature in Scotland. My employer have withheld income tax and NIC as normal on both items taking the tax code as a full time employee with my previous salary as reference. As a non-resident I cannot do a self-assessment tax return online. How should I progress to reclaim overpaid tax?

Hi Jacob Terpstra, 
You can file online if you purchase commerical software or you can file a paper tax return
Please see guidance here:
Tax on your UK income if you live abroad
Thank you.