DCMS has stated that visiting a business event venue for the purpose of viewing the venue for a future booking for a work-based event is permitted if this cannot be reasonably done from home (Covid Secure Safety guidelines must be adhered to while doing this). Viewings where there is not a permitted exemption for work purposes or otherwise, should not be taking place in closed venues at this time (25 March 2021).
In practice that means venue viewings for leisure activities is being treated differently to venue viewings for business activities as the former is restricted while the latter is permitted under the current guidelines. So this means that a show round for a conference or meeting is allowed but a show round for a leisure trip or a wedding is still not allowed.
Please do not hesitate to contact firstname.lastname@example.org if you have any other specific questions about the new restrictions and/or financial support.