551617 Google Calendar Parse

I use Google Calendar and they have an XML feed which shows your currently booked time via a feed. I want to make it easier for people to book a meeting with me. I need a script that will display my free time based on my 12 meeting times per week by cross referencing my calendar. My 12 meeting times are: Monday at 1 PM to 2 PM Tuesday at 9:30 AM to 10:30 AM Tuesday at 11:30 AM to 12:30 AM Wednesday at 9:30 AM to 10:30 AM Wednesday at 11:30 AM to 12:30 PM Thursday at 9:30 AM to 10:30 AM Thursday at 11:30 AM to 12:30 PM Thursday at 7:30 PM to 8:30 PM Friday at 9:30 AM to 10:30 AM Friday at 12:00 PM to 1:00 PM Friday at 7:30 PM to 8:30 PM I want someone to be able to pick a time and date and enter their contact details and it will email me an invite to the meeting. I would like it done in PHP so I can play with it after.