It would be doubtful that you would get a 100% mortgage for the full purchase price. 100% is nearly impossible (even with a fairly good credit rating) in today’s climate. Although things are starting to improve.You might be able to get a 95% mortgage with the deposit (the other 5%) being “Gifted” to you by a family member or friend. This is often referred to as a gifted deposit.
Another option may be a Homebuy Scheme, it is more or less a low-interest loan given to you as a deposit. You can read more about it here: www.home2own.org.uk you do however need to qualify for it and several areas have run out of funding.
Update
The government is relaunching the homebuy scheme under a new name and with different criteria as part of the drive to kick start the home building industry. Hopefully we will more news about this soon.