The CWGC website has been temperamental (at best) for almost a month, but has been restored fully this week. I'm on the site for several hours a day most days, including today.
So you should be able to access it now. In case you can't this is all the site says about access (nothing on there about the current Last Post ceremony)-
17 April 2023 WORKS STARTED for a duration of over 2 years (until approx. Summer 2025). From this day onwards: SCAFFOLDING is covering the Memorial and the name panels entirely. Two PEDESTRIAN TUNNELS give visitor access to and from the city. Two-way BICYCLE traffic and one-way VEHICLE traffic into the city will be possible at all times during the restoration, with the exception of the building and dismantling of the scaffolding. These periods will be announced in a timely manner.