Just look at the Fees and rates. Some have low fees but terrible rates. Others have high fees and better rates.
10 Popular Fintech Money Transfer Companies | TechBullion
I recently asked HSBC and they said the transaction fee was HK$ 280 per transfer. For your "couple of hundred" that's over 10% for the fee, not including any exchange rate losses or any charges at your UK bank.
like others have said, there's a per-transaction fee. so avoid frequent transfers if you can.
if you have a bank you've worked with back in the UK you should contact them and find out.
i've done it, it's a bit of a hassle and you can't keep all your money but bank-to-bank wasn't that much of a hassle or that unreasonable.
or you can go old skool and buy travelers checks.
I am following a discussion on another forum. There some participants from the UK seem happy with TransferWise.com. Disclaimer: I haven't tried it myself yet, but the fees involved seem lower then when using a international money transfer from bank A to bank B in another country.