The ECDL is worth doing, i did it 4 years ago and it's a qualification that is worth a lot more than CLAIT.
CLAIT is seen as an English qualification where as ECDL is, as the title says European. Out of the EC it is known as the International Computer Driving Licence. Lots of free sites to look on the net as well to help you study!
The NHS have embraced the qualification and see it as the course that most Trusts would like their employee's to have.
Your comment "is it worth doing, or is it too basic?" does depend on your level of knowledge already.