I have got 4th and 9th on two Clerical Officer tests, and 75th on an Executive Officer tests.
I found with the Clerical Officer tests: Practise the internet samples at home with a stop watch. I practised two nights before the test, so they would be fresh in my mind.
I was very careful with the English tests. I read the passages very carefully, and took everything literally. i.e. I didn't 'assume' certain conclusions based on the information. If they didn't say anything about e.g. Waterford train, I ticked the box for 'no information given'.
With the numerical, you just have to get a sufficient no. correct to get through, so don't try and do the last few qs. You can get bogged down in the figures if you are not careful.
The Classification and Clerical Checking tests were ones which anyone could do in theory. (You wouldn't even need a Leaving to be able for these). The challenge is to do these quickly and accurately. I just practised doing these very quickly and got most of them done. You need to be careful when filling out the answer sheet, as it is quite possible to fill out the answer to Q4 in the space for Q5 if you lose your place. I use a ruler when doing this.
Regarding your honours degree, this is not worth anything at the initial stage i.e. exam stage of the clerical officer recruitment. Technically anyone with a leaving cert could go in and do the tests. Of course if you get through the exam, the degree will count towards 'educational qualifications' at the interview stage.
At the exam stage they just want to isolate the people who are likely to do well on the tests. They understand that some people could be good at the work but may not have worked hard for the leaving cert, and therefore may not have gone to college. They also want to get people into the exam who are e.g. 40s and 50s, who may have worked in the private sector and want a change. I noticed when I was doing the exam, that there were a lot of people in their mid 20s. There was also a fair scattering of people in their 30s 40s 50s doing the exam. (As I am 35, I was a bit conscious of my age, as I thought most people would be college leavers & 20s)
You could also try applying directly to some city councils. Not every govt job makes people come to an exam. Some Clerical officer jobs are based on interview alone, and this may suit you better.
Good luck,
B.