Switch mode power supply
This is not suitable for your project, as it is not isolated. This means that your entire circuit will be potentially at high voltage. You don't actually mention what the circuit is, but I'm assuming it's not of the kind where a non-isolated supply would be acceptable.  

You need a supply that uses a transformer, which will isolate your circuit from the mains. If you are not experienced with designing power supplies, I would advise purchasing a ready made module this time round, both for safety and the fact switching supplies are little more complex than linear supplies.
There should be plenty of suitable switching modules around, check Farnell, Mouser, eBay, etc.