I used to run a will-writing business and I was worried when you mentioned the forthcoming home visit before. (The firm I ran traded exclusively through financial advisers, so I never needed to provide a sales pitch to potential customers). My advice is to get out of a contract that you DON'T need as quickly as possible.
As it's an 'off premises' contract (i.e. the salesman came to you, rather than you going to his office), you AUTOMATICALLY have a 14-day cooling off period to cancel the contract. [Part 3, The Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013]. Use it!