Const String to String issues

Thankyou Whandall this worked perfect. Can i ask how do i convert the other way?

I also need to read the string from the swSer.readstring but need to convert that so i can send via MQTT

Im reading the swSer fine and can print it to console but i need to publish this.

inString = swSer.readstring
client.publish("/spanet/serialdata/tx", inString);