Check Companies House for bankruptcy and how many times they have been bankrupt as this can happen several times.
Not just the couple of hundred pound subscription per annum type, where you can get your friends to write references to boost your ratings, proper National standing organisations that every couple of years visit your work to assess if your competent enough for their books. Who give you all the relevant updates associated with your field and provide all the support you need should you require specialist services.
Do not proceed without one. We use the FMB contract, however there are many generic contracts available. JCT contracts are common also. Get those payment terms sorted before you start. You never need to pay a deposit. All builders should have accounts and a 28 day Leigh way on payments. Builders should only charge for labour and materials delivered or ordered to the current date. If they don’t have an account, get suspicious!
Visit at least a current project, one in the last 6 months completed and maybe a verbal chat on the phone to another. If you can, choose the project you wish to visit from their portfolio.
They will be ‘living’ with you for longer than you have spent with the inlaws!!
Don’t rush your decision to choose your builder. Less speed, more haste.