It is difficult to give direct advice as the way your curriculum is organised will depend very much on your school. However, below are some general guidelines I find useful.

First - Look at the week as a whole, not day by day. Put into your timetable anything that's fixed, ie time in the hall, sessions with others, PPA etc

Second - decide how much numeracy you can fit in. I generally plan numeracy separately and timetable as a session a day. You don't want to miss it out. If you have someone else taking your class for PPA or supply etc. then you could pass on the numeracy to them.

Third - Look at literacy. I usually separate the skills/acquisition work from the application/development work. I then timetable the skills/acquisition sessions for first thing in the morning, get it out of the way. The application/development work might fit into the moe inquiry (and often does, particularly when I've been running one for a while) but my advice is don't force it! If it feels in any way coercive or incoherent then do something else. Retaining the trust and collaboration of the children while using moe is more important.

Fourth - Consider the scale of your moe inquiry. If it is very ambitious then you will need to look long term at how much time you will have to allocate to it to fulfill the commission. Be careful not to run out time before it’s finished. The children won't easily forgive disappointment, particularly if they have invested a lot.

Fifth - Plan how much of the rest of the curriculum you think will be explored during the inquiry. Of course this will change and shift into unexpected directions over time, but you can make some intelligent guesses at the beginning. I usually draw up a mind-map with activities and curriculum areas. From experience I can usually be confident to cover most of the rest of the curriculum, science, art, D&T, PSHE, history (depending on the topic), geography, ICT, music. And many other areas besides. I record these in my own copy of the national curriculum, which I annotate as I go along. You might want to design your own way of tracking and recording as it is obviously very important that the children get a broad and balanced curriculum and are not missing out on important areas of study.

Sixth - If I notice that some areas are not being covered sufficiently within the moe inquiry then I plan and teach those separately. Again this might be something you can pass on to your PPA cover.

Seventh - I try and avoid thinking of the subjects as distinct knowledge domains, but look at the way they overlap and combine. When I evaluate and record a session I think holistically and look at how the sign systems (in particular writing, drawing and enacting) are used by the children to represent their thinking and understanding. In this way I find we often cover large areas of the curriculum (and beyond) very quickly. Jerome Harste’s article – “What Education as Inquiry Is and Isn’t” is very useful in this regard (see the articles page).

Eighth - I'm also diligent at planning, noticing and recording the skills and dimensions of learning the children are using and applying. In particular, the key skills, thinking skills and social and emotional aspects of learning. Since these are fundamental to the children developing as learners and the main reason we use moe.Tim

I’ve just started planning my Mantle for this term and I found scanning through the Mantle website planning section really useful to get ideas as to how to structure it.
As far as coverage is concerned I started with knowing I was going to work alongside teachers looking at Culture in the Countryside. As I am not a huge rural fan I started thinking about what human stories I could use with this. Then I was hooked in and started researching the effects of the displacement of agricultural workers in early Victorian times.
So I was aware that my Mantle would be largely history based (my team will become time travelling archaeologists) so I was able to plan in the more obvious NC History strands. Then I looked at what Geography strands could be covered, then other subjects. Maths could be plotted in, otherwise it can be taught alone. As for Literacy all the usual objectives would be covered as there are so many good opportunities for writing arising from almost every session.
These were all strands that could be plotted at the beginning. I intend to highlight the areas covered and organise separate teaching sessions for the areas I haven’t. So, some planning is in advance and some in retrospect. I am constantly surprised at how much more I cover this way.
Hope this is of help to you! Dene