Good luck with your studies Elleanor.
By 'resources' do you mean concrete manipulatives?
You will need to be careful about your claim that Y6 teachers often focus on rote learning in favour of securing learning. I suspect many Y6 teachers would want to defend this.
Is it that you believe Y6 teachers might appear resistant to using concrete resources, the area that interests you.
Although you mention a current debate about resources in Y6, I think this is really a more general interest in the Concrete-Pictorial-Abstract approach to learning mathematics that has in fact been promoted in initial teacher education for over 50 years through the work of Bruner.
You may have enough research evidence to just focus on Y6 teachers and consider one or more of the following questions?
What concrete representations do Y6 teachers chose to use to support children's learning for certain parts of the mathematics curriculum?
What drives them to use these representations?
How does the use of the representations change how they would previously have taught particular areas of the mathematics curriculum?
What barriers exist that lead to Y6 teachers choosing not to use concrete representations in their teaching?
I hope this helps you.