I am a primary teacher specializing in the Early Years.
It's important to stress a few things:
1. ALL teachers in the UK, regardless of the age group they teach, need to obtain Qualified Teacher Status.
2. Qualified Teacher Status (QTS) is a certificate you can gain through many training pathways. Regardless of your training pathway, a QTS is an 'open' qualification, meaning you can technically teach any subject and age group you want.
3. The 3-5s age group in the UK falls within primary state education.
Here are some training options for you to gain QTS:
1. Do a BA Hons in any subject and then do a PGCE postgraduate course, which will lead you to your QTS.
2. Do a BA Hons in Primary education that has a QTS integrated.
3. Do a 'Teach Direct' or 'Teach First' programme, where you can be school-based, paid whilst doing your training.
Please stay away from any 'Early Years Teacher' training pathways. They do not offer a QTS and they technically only qualify you to work in private day nurseries, where pay is not good!