If you are on jobseekers/income support or on a low income there is no court fee payable on issue of the summons (you can get a leaflet about that from the court office). Otherwise you pay a fee according to how much you are claiming. If you are claiming a maximum of £300 for instance, the fee is £30, that is the lowest amount you can pay. If you phone your local county court, ask them to send a Form of Summns plus all the helpful leaflets including the one with a form to complete to prove low income so that you don't have to pay the court fee (best to mention that if you think you may be eligible).
It is important to write a "7 day letter" to the Company concerned before issuing a summons, one of the leaflets "Making a Claim" gives you a precedent for this. The leaflet "How To Make A Claim" tells you what to do, including how to claim interest and how to calculate it.
The court staff are very helpful to individual Claimants in my experience.
Also my experience with the District Judges who deal with small claims (anything under £1000 is a small claim) is that they bend over backwards to help individual Claimants. They know that some badly behaved corporates are getting away with murder in their way of dealing with consumer complaints.
You also have the full weight of consumer legislation behind you, even if you don't know all about it, the District Judge will. You can choose any County Court, it does not have to be local, my advice is choose a big court, like Croydon, they have the best judges and are quite up to date and good at dealing with telephone enquiries.
In a lot of cases, if you have a genuine case, the company will just file an admission and make a payment into court so you don't even have to fill in a form to get a judgement. If you apply for judgement, mostly it will be paid by the company by return. Thus far you will have been able to do everything by phone and by post, so no days in court!
Even if the company should decide to defend the claim, a hearing will be fixed within a few months and you and the Defendant just sit in a private room with the District Judge, no spectators! A lot of the time, the Defendant does not even bother to turn up, it is not worth the Company's while economically to send anyone along, if the claim is under £500.
So courage, mes amis!
Jan