There are many Schemes of Learning that are free to use and claim to be a Mastery Scheme of Learning.
True mastery learning is almost impossible in most school environments as the groupings need to be as homogeneous as possible, which is not how we run education in this country. Often, there are additional demands of having to follow a ‘timeline’, meaning that teachers feel they have to ‘move on’ before true understanding has developed. If you want to understand more about mastery learning, I suggest you read Mark McCourt’s (@emathsUK) book ‘Teaching for Mastery’ (978-1912906185).

I have worked at a school that subscribed to CompleteMathematics and have to say, that once you get your head around the platform, it is the best way of quickly understanding where a class is with their learning. It is really worth booking one of their free demos. The platform is just amazing for planning effective mastery lessons as it does not follow a prescribed timeline of objectives, rather allows you to plan for progress of the class at the pace they need, (further details on maths age can be found here or another about mathematical maturation here)
Firstly, you need to have a look at this YouTube video, explaining how, as we know, mathematics is a series of interconnected skills, and we need to master the prerequisite skills before we can develop onto the new skills.
The CompleteMathematics platform uses the concept of prerequisites for planning, so when planning you can determine the skills needed in order to be able to access the new skill and also where it builds to.
Here is a video demonstration of the platform or you can read an excellent post about it by Chris McGrane here
The platform is £950+VAT per annum, which in my opinion is worth it, especially when schools are buying sets of textbooks every year.
ARK Curriculum+ have a scheme for both Primary (Primary Mathematics Mastery) and Secondary (Secondary Mathematics Mastery). I have not had the opportunity to use either platform, apart from being shown resources by my wife, (her school Trust subscribed to the Primary Platform), so I cannot comment on the quality, but from what Mrs H has said, the plans are very well organised and structured even for a non-specialist mathematics teacher; although training on how to use them would have helped her far better. The AfL ‘supertool’ that is Diagnostic Questions by Craig Barton which has both a Primary and Secondary set of questions, that can be used for either, prerequisite assessment or post topic and the retrieval testing. Obviously, both can be set up in the Eedi platform so that all the work of creating a calendar is done for you.
White Rose Maths is a lot cheaper at £120 per annum and they have developed a scheme around a similar principle of small steps. This means teachers can begin learning the new skills for their class, once they have assessed the prerequisite skills and do not have to follow a ‘prescribed’ weekly plan. Prerequisite assessment can be done easily by using Diagnostic Questions which has a White Rose Collection. This enables the teacher to have a sets of prerequisite questions as well as sets of AfL questions available for each topic and this is also able to be set up in Eedi.
Further details of the White Rose scheme of learning can be found on this page.