Try entering payload.ts
in the top msg input field. The node needs the timestamp. As you did not feed it one it gave you the output for epoch which is midnight jan 1st 1970 so you get 00:00:00
You can also do this in the change node.
[{"id":"52919353.50ca94","type":"inject","z":"5a245aa1.510164","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":180,"y":2560,"wires":[["ee7bd564.7ecb58"]]},{"id":"ee7bd564.7ecb58","type":"change","z":"5a245aa1.510164","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"$moment(payload).tz(\"London/Europe\").format(\"LTS\")","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":390,"y":2560,"wires":[["596cd523.90c89c"]]},{"id":"596cd523.90c89c","type":"debug","z":"5a245aa1.510164","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":790,"y":2440,"wires":[]}]