No to worry. I worked it out
I added this line
<$set name="tags" filter="[<currentTiddler>] [{$:/config/NewTiddler/Tags}]">
and changed <<currentTiddler>> to <<tags>>
This is the final code, please let me know if this is the correct way to do it.
\define button()
<$button tooltip={{$:/language/Buttons/NewHere/Hint}} class=<<tv-config-toolbar-class>> actions=<<actions>>>
{{$:/core/images/new-button}}
</$button>
\end
\define actions()
<$set name="tags" filter="[<currentTiddler>] [{$:/config/NewTiddler/Tags}]">
<$action-sendmessage $message="tm-new-tiddler" title=<<journalTitle>> tags=<<tags>> text="""▴[[$(tid)$]]<hr>"""/>
\end
<$wikify name=tid text=<<currentTiddler>>>
<<button>>
</$wikify>