1.You can use the official website of Singapore post to track your package .
eg:RY202824204SG . Enter the tracking number, you can get the tracking details: Arrival at Processing Center in UK. But you need to know this is not the full list of your delivery base description, you have to select the destination country(eg.UK) and track your package in the official website of Royal Mail.
2.You can also try TrackingMore - a tracking tool to locate your parcel. This way is much more easier.
Enter your tracking number, and you can view almost everything in this page, such as tracking status description in origin and destination country, contact information, official website. You don't need to check your package in the offcial websites of different countries, this is really convenient and helpful.
Please remember the link : www.trackingmore.com