I am likely to go overseas (outside of the EEA/EU) in about 15 months for another 3-4 years
Suggest you read this from the
UK Council for International Student Affairs, especially
Box 3.
The
UK Case Law relating to this issue throws up some interesting cases. If you have a house in the UK that you intend returning to then see
Temporary Absence and Ordinary Residence in more than one place
Hope this puts your mind at rest.