I want to open an ISA in the UK with Vanguard, however I'm not thinking in staying in this country for the long term (maximum another two/two-and-a-half years).

This makes me thing that probably it's better to start investing directly from my country, however I'm not even sure I will retire in it.

This leaves me with 'the problem': opening bank/investment accounts and being able to move overseas while keeping them opened and working.

What are some long-term investment strategies to deal with the above problem?

Note: I'm not asking about how to select funds, ETFs and the like, at this point I'm only concerned about the bank/investment accounts 'flexibility' to move abroad.