I want to book a return plane ticket (Kunming - UK) and would like to find out if it's possible to buy the sort of flexible ticket that means you can change the date of the return flight without paying hefty fees. This sort of information isn't included in flight-search websites, so I'd like to find a trustworthy travel agent who can find out - and get me a good price.

Does anyone know of a good English-speaking speaking travel agent that handles international flights?