1. Pending the hearing of the custody case in September, you can apply for an access order on an interim basis. Essentially, the law does not allow one parent withhold access to children from the other parent. Accordingly, as soon as you can get an application for access into court, you will be able to obtain access to your children pending the hearing of the custody case in September. Be aware that all courts will be closed in the month of August, so it is essential that you get a solicitor who will act on this immediately and ensure that access is sought.
2. accordingly, go back to the solicitor who is representing you in the case in September and ask them to ensure you can get access on an interim basis pending the hearing of the case in September.
3. withholding access by you to your children is not legal. So get this sorted out immediately.