Lots of comments here talk about lack of distractions making it easier to get more done in the night. My case however is a little different. I don't know why, but my brain feels a lot more awake post dinner from 10pm to about 4am - than any other time in the day and this is irrespective of having slept well.
I may not be your target customer, so do take my design comment with a dash of salt.
1. Your site design seems to be targeting young children with the colors overflowing outside the borders, or yellow highlights on the text. Unfortunately it also makes your site seem not very professional.
2. After I choose a date for a lesson and a teacher, maybe the availability calendar could show me the same date I chose, so that I need not scroll to find the date I had already chosen
3. In the FAQ/Support section, do put in some information on payment modes - credit card, paypal etc.