No. Once the trust deed has been created you will need to engage the services of a legal professional to make the amendments required. This is true for altering the schedule to reflect an appointment or removal of trustees/appointors/beneficiaries and also for varying certain clauses within the deed.
If you do decide to vary the trust, you must take ample care to ensure that the change is effected in the way outlined in the existing trust deed. Should the variation not be consistent with the terms outlined in the deed you will effectively be creating a new deed in itself which is liable for stamp duty and other taxes, such as capital gains.