Timpg

Hi chaps, I'm in a bit of a predicament regarding a 2005 fiesta flame 1.4 petrol. I purchased the car a few months ago as a work bus, but since then it's been issue upon issue. Basically as soon as I bought it, I serviced it myself, flushed the coolant system through, changed oil, filters etc etc. I then noticed a very small coolant weap coming from the rad, passenger side corner, I weren't entirely certain it was from the rad, more like old coolant from when drained the system. There was also a whine/ squeal coming from the what I diagnosed as being the waterpump. I subsequently changed the water pump, thermostat, lambda sensor, aux belts, which seemed to solve the problems..... for a little while. I left work yesterday, got halfway home and noticed the temp gauge shot up and the rad fan was running ( note: I had my suspicions that the fan wasn't running when it should??), I pulled over straight away and turned the car off straight away and popped the bonnet to find coolant spraying out of what I believed to be the rad, but as the fan was running it was difficult to tell as it was going everywhere!!! Question is, obviously I need a new rad, but is there anything untoward that could have caused this situation i.e faulty coolant sensor?? I have suspicions as the fan only came on when the car overheated when the rad spat the coolant out. Next question is: is a rad change a simple job beings that it's got aircon?? Cheers in advance