The UK has become much less formal over the last 15 years, but if you have not met someone before it is still better to overdress than to be too casual. For men this means a suit and tie in London, although a smart jacket and trousers could replace the suit in other cities. For ladies the expression is smart business clothing, which is more difficult to define.
First names are used more frequently now, and the British will tend to follow your lead, so if you start using “Mr” or “Mrs”, then they will also. “Doctor” is usually reserved for medical doctors. Business meetings will usually start and end with polite conversation, known as “small talk”. The purpose of this is to find out a little more about you, and we know that some nationalities find this slightly frustrating as they want to get straight into the business discussions. The British will not be happy until they have gone through this stage, and your business will not progress satisfactorily until it has been completed.