Thanks for sharing your profile. Overall it sounds solid, and yes I feel you'd be considered at the UK schools you are interested in, with strong applications/essays/recommendations/interviews and an increased GMAT score.
The following strengths stand out to me:
-strong work experience at E&Y & PWC, both in terms of quality and quantity of years
-includes leadership and management experience; quant and analytical skills; international exposure; recognition along the way
-the volunteer work sounds interesting
-schools are looking for qualified female applicants; and there are generally fewer Thai applicants as well
And potential challenges:
-GMAT, as you know
-your goals-- would be great to further nail down
-just the general competitiveness of the applicant pool-- ensuring you show what makes you unique and what you'd contribute to the class
For US schools, may depend on whether you focus on i-banking or m-consulting. I'd probably look outside top 10 for best chances.
As for the GMAT, yes a 690 would help over 660.
And if still not 700+ it's up to you but certainly the higher you can get, the better your chances are, so might still consider it. Schools take the highest score. Focus on that preparation and nailing it next time if possible!
Good luck and keep us posted!
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