You must get ‘something’ in writing like quotes or estimates. Ideally this should be a standard contract for all the building works. Without one, neither you or your contractor will know what you agreed to.
If you agree on the contract in your own home, the contract must include reference to ‘cancellation rights’.
This is a legal requirement under The Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013.
This allows you to withdraw from the contract up to 14 days after signing. If there is no mention of any form of a cancellation notice, the contract may be unenforceable.
If the contract is agreed by distance - email, telephone or post, you must still be given cancellation rights. However, this does not apply if you sign or agree the contract on the contractor’s premises.
You can download a very basic example of a contract - click on the document above the contents. You can also search one from the internet, unless of course your contractor provides one, but do make sure you read and fully understand the entire document. For example, you should not be charged for ‘snagging’, so if itemised on your contract, do not agree and remove it.