Best bet if you want to book some frequencies is to call them and they will tell you and email address to send the frequencies you want to use to likely the email@example.com email address and then how to pay.
2nd Floor Riverside House,
2a Southwark Bridge Road,
Tel: 020 7981 3803.
We are open Monday to Friday from 9.00am to 5.00pm.
Fax: 020 7981 3235
If you require urgent assistance outside of office hours then please contact our Out of Hours Emergency Coordinator on 07866 423 619. Please note that all applications that are completed by the Emergency Coordinator outside of our office hours will incur a £55 admin charge in addition to the Licence fee.Here are the Application Forms you can use to submit for different frequencies.
Here is a Fees Calculator, if you are using radio mics then select the wireless mics option.