Okay, so that title might sound a bit off, please let me explain

I am currently in the process of developing a wildlife garden area for our animal rehoming centre, it is just in the early stages so final product will be in a few years. The main purpose of this was to allow us invite groups for education purposes to teach them about wildlife, how to use even the smallest space to create a wildlife friendly area. However, I am looking to the future and thought it would be wonderful if we could get a regular group of volunteers involved, this would be open to everyone however I thought it would be nice to cater it towards people with disabilities to give them somewhere to go and do something practical and rewarding. We do have some volunteers apply to volunteer roles within the centre, however due to the nature of the animals that we have (a lot have come from cruelty cases) it isn't always safe for them to get involved. So  I would offer them this role as another alternative to what we already have in place. 

But I was wondering if there was another way to get a group involved, for example is there any groups I can contact to set this up? Has anyone gone about this, if so how? How do I go about sorting this out and how to word appropriately? 

Thanks in advance!