Anyone working in schools, colleges or universities, in a teaching or non-teaching role,  has the right to join a trade union. There are a number of different unions in this sector who serve specific groups and focus on different strategies. However,  the main purpose of all unions is to campaign for better working conditions, negotiate pay settlements and defend workers’ rights.  It is up to the individual to choose which union, if any, they wish to join. 

Here is a list of the main unions in the Education sector:

National Union of Teachers
The NUT is the largest and most influential teachers' organisation in England and Wales. It is a trade union and a professional association, working on professional and curricular issues as well as conditions of service and pay. The NUT only recruits qualified teachers, or those who are on courses or in posts that will lead to teacher qualification, so it is best placed to speak on behalf of the profession. The NUT prioritises the interests of teachers, including all of their professional needs.
http://www.teachers.org.uk

National Association of Schoolmasters
Union of Women TeachersNASUWT is one of the largest teaching unions and the only one to organise in England, Wales, Scotland and Northern Ireland. NASUWT has members in all sectors of education and represents teachers in all roles including heads and deputies
http://www.nasuwt.org.uk/

Association of Teachers and Lecturers
ATL is a professional association and trade union representing over 160,000 teachers, lecturers and education support staff in England, Wales and Northern Ireland.  ATL members work in both the maintained and independent sectors - from early years through to further education - and include all those directly involved in the delivery of education to pupils and students.
http://www.askatl.org.uk/

National Association of Head Teachers
With a membership of over 30,000, the National Association of Head Teachers is the largest organisation of its kind in Europe. It has provided over a century of support to its members and works on educational issues covering primary, secondary and special school sectors.
http://www.naht.org.uk/

Professional Association of Teachers
The Professional Association of Teachers is an independent trade union and professional association for teachers, head teachers, lecturers, childcarers and education support staff. It works to promote the best possible practice in education and childcare and has around 34,000 members.
http://www.pat.org.uk/ 

University and College Union
Formed by the merger of two unions in 2006 the UCU represents lecturers in further and higher education and has a membership of 120,000.
http://www.ucu.org.uk/

Educational Institute of Scotland
The Institute has over 59,000 members, representing over 80% of teachers in Scotland, working in Nursery, Primary, Secondary and Special Education, right through to Further and Higher Education.
http://www.eis.org.uk/

Other unions working in the education sector with non-teaching staff are:

Unison
http://www.unison.org.uk/

Transport and General Workers Union
http://www.tgwu.org.uk/

GMB
http://www.gmb.org.uk/