Ian, the good news is that any reasonably-competent home repairer can undertake this job. Most spares that you will need are available from www.espares.co.uk but note that they are relatively expensive: you might want to check with a friendly local appliance shop as to what they would charge you. Make a list of what you need to replace, e.g. the square rear drum bearing to which you refer is available at:
http://www.espares.co.uk/part/tumble-dryers/creda/37745e/p/1088/720/0/420889/551453/square-rear-drum-bearing.html
I'm sure that when I last bought this, it came as only one piece of a full service kit (NOT the case with the eSpares purchase), so check exactly what you get for the price you are quoted - or you might end up with extra parts left over that you've also paid for.
R M Crorie
February 2008