Informal group of volunteers
You have indicated that you will not have any members, that you will not be charitable, that you will not incorporate, and that you will be led by volunteers.
There is not a formal legal structure available, but you can simply organise activities as a group of individuals. You will be unable to open a bank account or apply for grants on behalf of the group.
If you wish to have a legal structure, you could reconsider whether to have members. You could just have a small number of members (the people involved in your group), and set yourselves up as an unincorporated association. This would allow you to open a bank account and apply for grants.
Your route so far:
Voting members? No. Charitable? No. Incorporated? No. Paid staff in charge? No.