Along with a couple of the other posters I would agree that there appear to be a couple of areas you could cut back, so take some time out to investigate them:
Phone bill - Eu100 does seem extremely high, can you change provider and get a better deal -
www.callcosts.ie will give you an idea of who will give you the best package, if you have a relatively good idea of when you call, how much you text. Also have you and your flat mate considered getting a landline instead, it may work out better value.
Car Ins - i'm assuming thats you insurance, which without knowing your car / age, does seem a bit on the high side. Have you shopped around to see if you can get a better rate, i do it every year on renewal and the savings can be up to 40%! Has your car a large engine, could you move to a smaller car.
Car petrol - how many unneccessary journeys do you take? I'll fully admit that once a car arrived I suddenly became allergic to walking a few hundred meters to the shop! Stop driving home for lunch, what you're saving on sambos you're spending on petrol! Have you checked out if anyone in the area is likely to want to car pool, there was a website launched a few months ago, hoepfully someone can find the link - see about splitting the costs
Food - check out local markets / farm shops, between 2 of us we spend about Eu40 per week on food, buying from butchers and market. We can easily fill 2 large bags with veg for about Eu10-14! Supermarkets are convenient, but there is a reason they are so profitable! Plan you main meals, decide at the weekend approximately what you'll eat during the week, not planning can be costly.
Ad hoc house stuff... can you wait a couple of month to get some of the things? We're 5 months in our house, and having moved from a 2 bed apt to a 4 bed house we were 'short' lots of pieces of furniture, but we wait until we have the cash before we buy it. No kitchen table, but also no loan for a kitchen table. Just because 'everyone' you ever met has their places done up,doesn't mean you have to, and waiting can mean you get good deals when sales come up, we saved 50% on our floor tiles.
Credit Card - definitely take some time to shop around, interest free is where you want to be!
As an aside I have found 2 books good for helping to identify the financial pitfalls we face, what I like about both of these books is that the authors have been in debt and have gotten themselves out of debt:
Your money or your life - Alvin Hall
Debt-Proof Living - Mary Hunt
While these aren't Irish writers, Alvin is American writing for UK market and Mary is American writing for american market, both have good strategys for handling your money.
Congratulations on getting on the ladder, and we know you can make it.