Hey Simon
You mentioned that you are interested in trading gold.
An easy way for you to do that would be to use the bullion ETFs listed on the SET.
There are 2: GLD and TGOLDETF.
GLD has better intra day liquidity (trading volumes) and so should provide you with less risk.
You have probably already read this article but here is a link anyway:
Guide to Exchange Traded Funds in Thailand
Take care to read the paragraph about risk and liquidity.