Apply in Vietnam ——Can I leave Vietnam?

I had no experience applying for a Vietnamese visa the first time,Only applied for 15 days（to Mar.31），My visa status is currently pending approval，If I haven't gotten approval by then, can I leave Vietnam and just travel around the neighboring countries?

Who do you get to sign your Proof of Life document.

Hi any one on this forum can advise.. I lived in Bangkok for 20 years plus had a company and work permit ..I started drawing my Thai government pension two years ago but now I'm in the UK it stopped last month the reason being I have to show "proof of life" I've tried the embassy in London with no success anyone got any ideas of how I can show "proof of life" without having to fly back to Thailand at the moment as I'm planning that next year..any sound and solid advice will be much appreciated..