The first step is relatively simple, and it is just to ask the executor/trustee for the information, where there is no need for the involvement of the court. If the trustees agree to provide the information, then usually the beneficiary will meet the cost of copying and sending the documents. However, if the trustees refuse, then a beneficiary can consider making an application to the Chancery Division (Part 8 claim for under CPR 64). This is an application for the determination of a question arising in the execution of a trust.
Who pays the costs for the latter application is at the discretion of the court, and a costs order will usually reflect the outcome of the application, meaning it could be the beneficiary (if unsuccessful), or the trustees (if the court discloses that they acted unreasonably) that pays the costs. Alternatively, the costs could also be payable out of the trust if it is considered appropriate.