I assume that you will be appearing in the Small Claims court which is in the Thomas Moore building. You get to the TMB through the main entrance on the Royal Courts of Justice on the Strand. It's a bit of a trek through the RCJ to the TMB. Be aware that the Thomas Moore building is served by two lifts which only hold about 5-6 people at a time and quite often one is out of action, so be prepared to queue! There aren't any public stairs to all the floors. Only the court staff have normal access to the fire escape stairs! The Small Claims suite is on the fourth floor and is quite compact and modern. The actual court rooms (there are 2 of them) are fairly small and not at all imposing. The judge sits at the same level as the parties and is only about 6 feet away. The procedure is very informal. Evidence is given while seated and not taken on oath. The judge takes an active role in keeping things moving and prevents the argument from straying off the point. Yes, you call the judge Madam (unless of course he's a man, but I'm not aware on any male district judges currently sitting in the Small Claims courts). The proceedings are recorded automatically and you can, if you want, pay for a transcription to be made of the proceedings, but this can be quite expensive. You can make your own written notes, but you need the judge's permission to use a tape recorder etc. Phones should be off or in aircraft mode.
There's no usher in court (or anyone else* apart from the judge and the parties) and so if any thing like an exhibit needs to be handed to the judge, this is done by the party concerned.
Assuming that your written claim is fairly clear and covers all the points you wish the court to be aware of, you may only need to summarise your claim verbally, especially if the defendant doesn't show up, as the judge will have read all the papers beforehand. The judge will obviously test any aspects of your claim which need clarification, as will the defendant if he is present. The worst case will be if the defendant turns up with an advocate (probably a solicitor). Clearly if this occurs, your claim will be subjected to more opposition, and no doubt some elaborate defence will be put forward. Should this happen and it involves a good deal of 'new' (to you) law or legal submissions, you can ask the court to explain anything which you don't understand, especially if you have been ambushed (ie this is the first time you have heard this 'defence'). The court is well used to litigants in person and will expect to guide you through such things.
If you get a default judgment, I would expect the judge to give this verbally (ex tempore in legal jargon) on the day, possibly following a short adjourment. However if there is some heavy duty legal submissions from the other side, the judge may well reserve judgment to a later date. This judgement will be written and give the judge's summary of the issues, outline the relevant law and provide a full assessment of how she reached her decision. Following judgment, assuming that you win, there will be an assessment of damages and costs, which will be followed with a written order. If either party seeks to appeal the judgment or the defendant seeks to appeal the amount of the damages, the first opportunity to raise this will be at the end of the proceedings when a losing party can ask the judge for permission to appeal, which requires an outline of the grounds for appeal. If the trial judge refuses permission, an appeal application can still be made to the IPEC or the High Court within 14 days of the judgment being handed down.
By way of preparation, I suggest that you also download and take along a copy of Part 63
of the Civil Procedure Rules, and Practice Direction 63
(both obtainable from the justice.gov.uk web site). Note that only some of the PDs apply to the Small Claims track (see para 63.28 of Part 63). There are other parts of the CPR which may be mentioned in court, but I don't think you need to worry about them as the judge will explain what they mean as necessary.
It won't be nearly as nerve wracking as you anticipate. Good luck, and don't forget to let us know how you get on.
*Technically speaking the public are allowed to attend, but this is most unlikely.