Set smart-time value at explicit time for today, using current time zone

[Keith Harris]

Using smart values in setting up jira automation, I am trying to set a field to the current date but at a fixed time (namely 6am).  My time zone is currently BST (UTC+1), but for half of the year it's GMT (UTC).

So, using the below my ticket creates with the field set to 25/04/2024 07:00.

{{now.withHour(6).withMinutes(0)}}

I've tried to get around this by playing with the following parameter (timezone), but same result.

(Europe/London)

I want to get around needing two sets of automation rules (one for each timezone, set up as 5 and 6 using the withHour parameter), or needing to flip the automation logic twice a year.  Surely there is a way to use smartvalues to inform that you want it to use the timezone set at the system level, which flips in line with UK daylight saving?

I've searched and can't find the answer - I wondered if it's possible to join a smartvalue date and a text string of "06:00" but I don't think so.  Any help?