What can you do?
What can you do if the work is not done to the standard that you expected? Or if the cost increases substantially? Or if the builder "goes bust"?
Sometimes, builders and their employers fall out. It happens! It does not have to end in a dispute, but where feelings run high it often can do. It is always in everybody's better interest to take out as much heat as possible and seek a resolution that is fair to both parties and is also legally binding. In this case, it is best to seek professional advice early! No-one wins once it gets into Court.
Once you have decided to have substantial building work done you usually have to have building drawings prepared. Then you may decide to ask for quotations or estimates. Be aware that there is a big difference between the meaning of those two words.
A legally-binding contract does not HAVE to be in writing, but if yours is not then you may be at potential financial risk. TAKE ADVICE.