Battery is on the way out. Tested it again with the multimeter and a reading of 11.88 was shown. This represents a low battery, 10.50 being flat and 12.70 being fully charged. Although 11.88 doesn't seem like much of a drop, in reality the battery has only about 30% power (max) . Priced a few batteries up and will buy a new one and fit it on Wednesday. Also will buy some heavy duty jump leads, you never know when you might need some. Haven't checked the power from the Alternator though, but I am pretty sure it's the battery that is on it's last legs.
To test a 12v battery's charge or voltage, make sure that the battery has not been charged for at least 2 hours. Turn the multimeters dial to 20volts DC (batteries are DC mains is AC) put the red cable into the Volt/Ohm socket on the multimeter and the black cable into the Com socket. (Com means Common or Earth/Neutral). Now place the red tester onto the + positive terminal of the battery and the black tester onto the - Neutral terminal, read off the numbers on the multimeter.