There are four direct and indirect flights connecting Southampton and Singapore every week, with the journey taking 24 hrs 20 mins on average.
Or, if you're fairly flexible on dates, try to get a last minute-deal by regularly checking the Netflights website.
Singapore actually has one airports to choose from – but Singapore Changi International Airport (SIN) is the usually the cheapest option. If you need to fly into a specific airport, adjust your search to focus on those flights. The most popular airlines include Lufthansa.
But if you can't find one which is right for you, try looking at flights to other cities in Singapore to check out some other options.