Code.org is a great website where teachers can find out how to go about teaching Computer Science to their children and the pupils can in turn discover the basic concepts of Computer Science and learn how to write code with drag and drop programming. The site, although designed to target schools in the USA, is well thought out, child friendly and supported with good instructional videos; all of which makes it equally suitable for teachers and pupils within in the UK.
Teachers can sign up for free and receive access to all the training materials required to teach their children an introduction to coding. This introduction course is split into 20 stages, each approximately one hour long and supported with all materials necessary including, tutorial videos by such luminaries as Bill Gates and Mark Zuckerberg. A full lesson plan, which can be adapted to your requirements, is also included for each stage. In addition, the teachers are provided with a very useful overview as to how each of all their registered pupils are progressing through the course and of any difficulties experienced.
Pupils can learn the basic concepts of coding with drag and drop programming (similar to Scratch) using a game format that includes Angry Birds and Plants vs. Zombies as characters. The introduction will allow them to learn repeat-loops, conditionals, and basic algorithms. The materials provided support the learning and will allow children to proceed at their own pace. Progress trophies are awarded and saved on the student record and certificates are also available and may be printed out.
There is also a taster called Learn an Hour of Code which is basically Stages one and two of the introduction course. This taster can be used to see if it suits you and your class without registering on the site. You can also access the rest of the full introduction course here without registering; however, this will not allow you to record pupil progress or access the lesson plans.
Why not give the Learn an Hour of Code a go and see if it is for you. I believe that you might enjoy it and will then want to further your coding experience by making use of the rest of the introduction course and its materials.