Yes, get a couple of quotes first, but recommendations from a trusted friend or relative is always best. Beware of the type of builder who seems to think a job is more complicated and 'ums' a lot and the kind who try to blind you with science or patronise you.
There are plenty of good builders out there, and you may have to wait after your quote as the best are in great demand.
Never, ever pay up front. A reputable builder will have an account at his local building suppliers. If he needs money to buy materials it suggests his credit isn't good and he's not trustworthy. If it's a large job (say £10,000 or more) or more then agree to pay him half way, or at regular intervals, for work done and materials already used.
We've renovated two houses, in different parts of the country, in the last 10 years so have a good grasp of how it works. And finally, don't worry about asking for your quotes. Most reputable builders know you win some and you lose some.