The clicking sound normally indicated that the solenoid is not working, this could be the problem. You could try a direct electrical contact to the starter motor this would tell if the starter motor is ok.
Hi there, it might be worth just taking the terminals off the battery and giving them a clean before you start to look at the starter motor. I had exactly the same problem on my old car, the contacts on the battery worked loose and were a bit cacked up, a bit of a clean up with some wire wool and all was fine. It's worth a go just to be sure.
You will have to disconnect the battery anyway if you need to check the contacts on the starter motor so do the both jobs at same time. You'll have to get underneath to check the starter motor connection. There is only one large diameter cable going to the starter from the battery but DISCONNECT the battery before doing anything otherwise there will be big sparks flying if the cable touches the chassis (which is used to earth the whole car). If you are in any doubt leave it to an experienced person.