The procedures involved in litigating in the Small Claims Court are usually informal. The costs of the litigation are at the Court's discretion, but usually, the loser will pay the other side's expenses but not their legal costs. There are however a number of alternatives to issuing proceedings. Firstly, be prepared to complain whilst you are still abroad. If you complain on site to the tour rep and the hotel manager the problem can most likely be sorted out.
Most companies have standard complaint forms ask for one.
If your complaints are not actioned ask why and try and get the reasons confirmed in writing. If the tour company say, for example, there is no other available accommodation check it out, ask other holiday makers if they are happy where they are and find out where they are staying and see if there are any vacancies. If the tour company will not move you, then you can move yourself subject to paying the bill at the new accommodation and then sue the tour company for the difference on your return. If the accommodation has a minor problem such as dripping tap or ant infestations complain to the hotel management and see if you can be moved. If you have a complaint against an ABTA member, you can discuss your complaint with ABTA's Information Bureau.