buying a property with a friend

[classonglass]

i have been offered a chance to buy a property with a friend the idea goes like this i am in rented accomadation paying �400.00 dead money we get a property together 50% each say i pay �300 .00 a month and he pays the other �300.00 thats a �600.00 pound mortage i live in the house pay all the bills etc but any work on the property house is split between us then with any spare money i have he has agreed to match eg i put a extra �250.00 on the mortage one month or say every month he will do the same his angle is if we pay extra on the mortage it will reduce costs on the actual mortage every month plus its a long term investment for him my problem is it just seems to good to be true would he be able to take a loan or remortage on property with out my knowledge etc he is prepared to have a legal contract is it worth the paper it is written on plus if he decided to pull out would i have to pay the whole mortage myself etc