Dabz is right.
There is another problem with this scheme. The purpose of the deposit is to make you save.
Savings makes a massive difference to your wealth.
After 20 years or so you can own a house, but it doesn't happen by accident or through fancy schemes.
I'm sure there are people at WB who have a lot of equity in their home and have a decent pension fund and have six figures in assets. You won't be able to spot them though because they probably aren't the ones flashing the cash.
Did the "haves" get on some clever scheme? no they just saved and over a period of time it makes a massive difference.
The problem with your scheme is that whilst short term it might get you on the ladder quicker which might be attractive, it doesn't change the fundamental fact that if you want to be wealthy long term you need to save and whilst you might be putting that off until you've got the house, believe me it only gets harder once you've got a house and then kids.
I recommend reading this wll known book
http://www.amazon.co.uk/Millionaire-...=1H57N0SMVKJWE
Do some more research before you make a decision that could affect you for a long time.
Hope it all goes well.
