Well meaning advice offered so far, but not very helpful as it is inaccurate in many respects, I will come back to that in a moment though. I would like to clarify something, a Civil Summons is used in District Court proceedings i.e. for amounts under €6348 but you said that the amount the plaintiff is claiming is €8000 which would mean that it is Circuit Court proceedings, which would also mean you received a Civil Bill instead of a Civil Summons. I'm not being pedantic for the sake of it here, because there are important differences in the applicable procedures in whichever is the correct Court, and it is therefore important to know what you are dealing with.
1. If you do not defend the matter it will not appear in any court list and judgment will be obtained against you by the plaintiff lodging the
necessary papers in the relevant court office. If you wish to defend you will need to do the following: If it is a Civil Summons you will see that there is two Notices of Intention to Defend, one of which is to be filed in the court office and the other one served on the plaintiff/solicitor for the plaintiff, only when this is done will the matter will tappear on the court list for the specified date, on that date the judge will then usually set a hearing date. If Circuit Court the procedure is more complicated, very basically an appearance must be entered, then defendant raises any particulars, then enter a full defence and then any discovery applications, etc. and then Notice of Trial will be served and the hearing will take place.
2. If you defend the matter just to explain yourself (particularly if Circuit Court) you will be massively increasing the plaintiff's legal costs which you will ultimately be liable to pay. Also if Circuit Court defending an action is very procedural and would probably require a solicitor and probably a barrister. If however, it is District the costs won't be as high but you will be increasing them nonetheless if you choose to defend the action.
Op you should probably go see your solicitor who will be in a better position to advise you regarding your options, or perhaps even MABS.