To answer both points above, I'm certainly not advocating that any council should ever restrict access for anybody to any information (unless required by law, obviously), but the legal framework does permit sub-committees to operate in secret, so this is reflected in the model standing orders. I deal with random enquiries from parishioners and occasionally others on a daily basis and I often wonder about their motive in requesting the information, but without a legitimate reason to deny, I always provide access. It may just be a coincidence, but I've never received an FOI request.
The model standing orders don't conflict with the LTNs. Sub-committees usually report to their parent committee, so information is shared. The position regarding members of the council attending sub-committees is less clear in the case of a council that closes its sub-committee meetings. If the resolution to deny public access states that only members of the sub-committee may attend, then only members of the sub-committee may attend. If it states that the press and public may not attend, other members of the council may be permitted to observe.