I suggested the 0.6 thickness because it is a fair compromise between a thickness that gives lightness to the PCB but at the same time the necessary structural strength to be able to weld the components on both faces (if you use double side).
Moreover, about?the?PCB manufacturer, there are probably many good ones, but I told you about JLCPCB because that's what I and other fellow launchers used: it is cheap and the product is of very good quality. Shipping times are long enough but acceptable. As for Italy, where I live, the wait is three weeks, from the moment the order is sent by web, to the sound of the intercom from the postman on my way.