Chirping is the power sounder complaining that battery voltage is low so could be the battery dying. Whether that's because the battery is at the end of its' life, it's not being charged properly, or something is draining it when the car is parked up requires further diagnosis.
This is what you need to do:
http://www.omegaowners.com/forum/YaBB.pl?num=1225724099I appreciate that it's not the easiest set of tests to do when stranded but a cheap multimeter from a hypermarket will tell you all you need to know.
Failing that, get a jump start and keep a set of jump leads in the boot. If, after a jump start, you can turn on a good amount of electrical load without the engine dying the chances are it'll get you to the ferry as long as you don't stop the engine!
The crimp connector at the battery positive terminal can be problematic and is something that's easily fixed. Check that this is not getting hot with the engine running and that the crimp where the large cable from the engine attaches is not loose.
Kevin