I got an A* in CCEA History. Don't see many NI people on here so glad I found at least one. At our school the AS modules were Germany and Italy, not Russia as you seem to have done. The A2 modules were Ireland and Russia. Which modules are you doing currently out of interest?
Unlike yourself, I excelled at the source-based modules (got full marks in the Germany and Ireland modules, and a good deal lower in the other two, essay centric modules (though I'm not complaining!). Strangely, I also put far less effort into revising for the source-based exams. The other two papers I found much harder, therefore I concentrated my efforts on these weak points of mine. Though as I say, it still yielded significantly lower UMS marks for me than in my strong modules, Germany at AS and Ireland at A2.
To be honest, the A* was more of a nice bonus than an absolute must for me. Personally, I was much happier scraping A grades in my other two A levels (Chemistry and HE) than in getting the top grade in history.
I'm not sure what I can offer in terms of concrete advise, you will already no doubt have your own strategies for revising and for the exams themselves. You say sources are your weak spots; my best advice is, remain calm. Seriously. The best way to ruin an exam performance is to get uptight and nervous, which will throw your analytical and thought processes down the drain, skills you will need for these papers. Try not to get too bogged down in the old author, motive, date ect routine teachers sometimes lean on rather heavily. Yes, these are important considerations, but such an approach tends to produce a bland, generic response which the examiners will not credit highly. Be specific to the source, refer to its content exactly, and most importantly but often forgotten in the heat of the exam: answer the damn question! Not what you think or want the question to be. At all times, remember to answer the question in terms of how the examiner is looking for it to be answered. Simple, yes? Its amazing how often basic exam technique is thrown out the window at the crucial time. Sources are not evil texts of writing with more hidden meanings than Egyptian hieroglyphics, they can be straightforward enough if you tackle them in a logical, common sensely, structured manner, honestly!
You are obviously an intelligent person. Go in there and make sure you give as good an account of yourself as is possible. If you do that, you will have no regrets whatever the final result. Believe me, I know
PS It seems appropriate to say (though I don't belive in it): good luck! If you have any specific queries re the way to approach sources or the actual content of the Ireland module, please don't hesitate to ask.