Silver solder is used by model engineers frequently, and the epicenter of model engineering, the UK, is close to you. Lots of links for suppliers and books
http://easyweb.easynet.co.uk/~chrish/links.htm
Think of brazing rather than soft soldering – SS is more like that – ie getting the parts just turning red hot.
Like mxtras said, cleanliness, flux and the right temp critical. A bucket with a sealed lid of 10% sulfuric acid makes a nice pickle for before and after.
Stay away from acetylene unless you’re experience, you can do it by playing the flame, but the flame is too hot and easily burns the flux. Propane’s the right thing to use. If you here someone complain that their handheld bottle didn’t work, it’s not that the gas isn’t hot enough, it’s the torch is too small – not enough btu’s. If your stuff is small, not and issue though. I use a largish torch with changeable tips on a 20lb propane cylinder (very useful for heat treating as well)… then you don’t run out very often.
It takes very little SS to make a good joint, similar to Al’s preformed solder idea, I get the smallest dia SS and cut it into maybe 1/8” long pieces placed into the wet flux along the joint. Carefully heating so as not to blow the pieces away, you get a very neat joint when it all comes to temp.
Another handy idea is a using three refractory bricks to form a corner. They reflect the head so well it really quickens the process.
Both the fumes from flux and solder (cadmium) is toxic, so consider a hood (now you have to learn sheet metal work to) and fan. There are special non-cadmium SS’s if you are making anything for food.