There are actually two different cleaning procedures and agents to do the job. To keep mineral scale under control, most of us use a dilute solution of Citric Acid. This can be purchased from most supermarkets and located in the Spices section somewhere, usually where Cream of Tartar, etc can be found.
The other cleaning job that most of us do, is to clean the PF Baskets, Shower Screen and Water Dispersion device(if fitted) in Espresso Clean which can be purchased from our good friends at Coffee Parts, a site sponsor. Since your machine lacks a 3-Way Valve, it is not possible or desirable to allow Espresso Clean to find its way into your machines water circuit back through the ThermoBlock, etc. The above items just need to be removed and soaked in a weak solution of Espresso Clean as per instructions on the pack. If you do this regularly your machine should be able to provide you with good service and good coffee for the duration of its design life.
Something you might like to consider though, is whether you can locate and use non-pressurised baskets in preference to the pressurised baskets that came with your machine. You would need to get a reasonable quality grinder though to go down this path but the end resulting improvement in the quality of your shots would be worth it, Im sure. Anyway, hope this helps you out some,