There are so many different postgraduate study options available in the UK. Here is a very brief overview of what's available after your first degree.
This is the most popular postgraduate qualification They can take between 1 to 2 years to complete and usually build on the knowledge and expertise you developed in a first degree. Some Masters will allow you to change from the subject of your first degree, but you will need to check the application criteria.
They can be taught courses or research based. Some examples are:
Postgraduate Diplomas and Certificates these are shorter courses at the same level as a Masters, with fewer credits and you won't have to do a dissertation.
Professional/Vocational qualifications. These involve helping you develop practical skills needed for a specific job and usually include an element of practical training. These are usually accredited by the professional bodies representing people in those professions.
Conversion courses vocational postgraduate qualification allowing you to study something different to your first degree.
Master of Business Administration. This is a globally recognised qualification which helps you develop skills for a leadership career in business administration and management and covers all main aspects of business. Entry criteria usually requires some real-world business experience of at least 3 years or even more.
PhD stands for Doctor of Philosophy. This is the highest educational qualification you can get. They can take between 3 to 6 years depending on whether part time or full time. You will need put forward a research proposal as to how your research is new and will add to the existing knowledge. You'll also have to do a Viva where you orally present and defend your thesis to a panel of experts.