Assembly Hall reserve / sinking fund

We plan to set up a reserve / sinking fund to be used solely for improvements and repairs to the Islington Assembly hall and planned to be financed by a £1 plus VAT levy on each ticket sold. This should be a straightforward process which does not raise any legal or code of practice issues, however as the hall is used as a commercial venue there will be VAT implications. Has anyone had experience of setting up similar arrangements and are there any other issues we need to be aware of? Thanks, Mark Badcock