This sounds like a brilliant local History project. I think the idea of the on site visit and the Museum trip is great. It would give the children a real life connection to the history. It is very important the the students have time to complete a number of lessons and hours using the Minecraft Education app before doing this project. They will need to be comfortable and competent in the technology. Group work is essential throughout the project and I would suggest the groups are decided upon before the project even begins. Mixed ability small groups tends to work best for these projects. I really like the Idea of having the guest speaker and visitors in to explore the project on completion. this will give the students the opportunity to share what they have built and to reinforce what they have learned. Well done.