Hi Sylvie,
So you can apply for the visa yourself, or we can do it for you via our visa service.
10 weeks before you're due to depart, we will send you information on how to get your visa, including your application form and details of how and where you can make an appointment. You then have the option to complete the application yourself and book your appointment, or you can return the application to us and we will fill it out for you and arrange your appointment.
Once you have been to your appointment it will take 4 working days for your visa to be processed and sent to you. You're correct that you will need to leave your passport at your appointment location for those 4 days.
I hope this helps, but please let me know if you have any further questions.
Many thanks,
Vickie