Help to cancel Contract of Sale

My dear brother-in-law, the poor guy who has just bought a property at the weekend at the auction. However after getting some advice from the tradesman, the renovation is going to cost more what he estimate budgets. This causes him a lot of worries and a sleepless night last night. After getting serious thought and discuss with his wife, they decide to end the contract.

Of course, they need to talk to their solicitor on Monday but he eagers to find out if he can cancel the contract given the following reasons:
– The property was passed in at the auction and the RE negotiated with him who had the highest bid. After a lenghthy discussion, negotiation the vendor acceptted his counter offer after the auction. Can he end the contract with the reason that the property was not purchased at a publicly advertised auction? The property was passed in at the auction.

– Can he end the contract with a reason of finance not approved although he did not put a condition of subject to finance before signing the contract?

I believe that there are someone out there who has some knowledge about this situation should give hime some advice before he talks to his solicitor on Monday.

Note: He has not paid 10% percent deposit yesterday, only a small amount of money. The rest of 10% percent has to be paid off on Monday.

Any advice/thought would be appreciated.

NewStart