Contracts I - The Basics
A contract should include:
Contracts II - Where to get one
The First Law of Home Renovation: No job is as simple or as cheap as you think.

Job description: Remove a brick wall in a corner that formed a cupboard. Removing the bricks was straightforward, relatively fast and easy, although it created plenty of rubble. Afterward, the wall and ceiling needed painting - white for one, yellow for the other. The ceiling needed a minor repair, and a disused gas pipe was exposed and had to be removed. Note the dust covers. They did controll most of the dust but the kitchen was out of bounds for the duration of the job.
JCT - Joint Contracts Tribunal The industry standard, providing contracts for projects of all sizes. The JCT website (www.jctltd.co.uk) provides comprehensive, often complex, information on the full range of contracts. It has links to information on homeowner contracts and to shops which sell JCT contract forms. It also contains valuable information on disputes and adjudication.
The Guild of Master Craftsmen (www.guildmc.com) has prepared a set of contracts which vary according to the size of the job. Guild members come from more than 400 trades, from antique restorers and blacksmiths to gardeners, glaziers, roofers and woodworkers.
Via Your Insurer Homeowners who have a Legal Services add-on to their general insurance with MORE TH>N can get a solicitor-vetted contract via their insurer. The process is an interactive one - you supply the basic information, and their solicitor ensures your details are okay - and is done via the More Th>n website. Your "Small Scale" building contract " sets out the terms of the work to be carried out. The contract makes sure that the job the builder is required to do is clearly stated, that, if applicable, the materials to be used are identified, and the time when the work is to be completed is agreed. The contract will also fix how much the works will cost, and gives people the option to specify that the builder has to 'pay a penalty' if the work is not completed on time."
DIY You can make your own contract. A simple Letter of Agreement spelling out who does what, and when, and who pays how much, and when, can do the trick. Just make sure it is comprehensive and includes clauses concerning penalties, dispute resolution and other key issues.
Contracts III: Cons as well as Pros
A Standard-Form contract unambiguously sets out the basic terms in a widely-acceptable and comprehensible form. However, the forms were devised by professional organisations "primarily for the benefit of their members in the industry, not the consumer. Some procedures provide a mechanism for unreasonable money claims or extension of time claims by builders." Benjamin Mee, Which Guide: Getting the Best from your Builder, p.41.
Contracts IV - When a Contract Isn't!
A contract is a contract is a contract - so read it carefully before you sign. BUT - a contract may contain one or more unfair terms, and they are NOT binding.
What is an unfair term? A term is unfair if, contrary to the requirement of good faith it causes a significant imbalance in the parties' rights and obligations under the contract, to the detriment of consumers. 'Good faith' means that traders must deal fairly and openly with you. Although standard terms may be drafted to protect commercial needs, they must also take account of your interests and rights by going no further than is necessary to protect those legitimate commercial interests.
Did I write such fancy language? No, I didn't. The government did.