The coolant light has just come on, can it still be driven...and can i change this myself or take to garage?

Possible water pump failure. Was temp guage showing "hot" ? , if not maybe coolant sensor issue. Had the car just been driven hard ? Any pressure in coolant expansion tank ?

Look for signs of coolant leakage on the garage floor, driveway or ground under your vehicle. Check the level of coolant in the overflow reservoir or inside the radiator by removing the radiator cap. The engine must be cool before the radiator cap can be safely removed. Inspect the radiator to find where it is leaking. There may be an obvious hole or other defect that is easy to spot, such as deposits of coolant and an orange or green discoloration. You can refer this link http://www.buyautoparts.com/radiators.htm to learn about radiator.

It depends on the vehicle. Thermostat is normally in the water pump housing. You can change it yourself but typically you will need to flush the coolant afterwards and/or burp the system due to air that will get into it when you change the part. I would recommend taking it to a local garage to have done. Part is about $45.00 and labor shouldn't be more than an hour plus a gallon of coolant.

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From the way you describe it, It is likely the pressure cap on the surge tank (expansion/overflow coolant tank).
It is probably worn and no longer able to hold the pressure.
The cap is an inexpensive replacement so do this first.

take a look at the waterpump, these cars have problems with waterpump leaking, take caution, the waterpump is driven by the timing belt,if that belt pops or jumps due to coolant leaking on it and causing it to fail,then you will have a costly repair,i belive its about $4,000 to fix, it will cause cylinder head valves to bent, have this coolant leak check asap.

catalyst temperature sensor failure ,whats causing the sensor to go wrong?? most likely cause is a weak mixture ,or burning water ?? loss of coolant ?? Try fitting a bosch sensor and not a cheap chinese one.also look at the old sensor to determine if its white and burnt .failing which a ford garage who can adjust the mixture with the ECU unit

It means that either the coolant level is low in the radiator OR sensor which causes that light to come on is bad. Check the coolant level and check for possible coolant leaks. Do you find antifreeze on the driveway or garage floor? If the coolant level is OK and no coolant is found on the floor where the car is parked, the sensor is bad. The coolant level sensor is located in the plastic coolant reservoir tank. It's easy to change and not expensive.
Charlie

have you totally cleaned the fuse box and fuses

sounds like headgasket , when it si done you must make sure you fill with water and no aIR BUBBLES IN SYSTEM .i did one once took me 4 hours with a hose pipe ramming water into it heater matrix first then engine .i had a garage do the gasket 1st time they did not fill with water properly and it blew had to do it myself