Welcome Lewis .
Once you are in regiment after (first 6 months). Someone could send you your stuff. Would you be able to wear it officially ... probably not, but who knows... Maybe someone who currently serve can answer that question, but we are in shortage of active legionars here. Last active on forum and FFL was banned for being a prick to everyone.
Items you listed are among those you buying yourself in FFL so... I don't know if you are allowed to buy things only from legion inventory (you can definitely choose what you want from it), or you can buy what you wont.
That other option is probably available if you already serving for some time and depending on regiment and your superiors.
You can take your daysack for sure. It would be given back to you along with other of your stuff once you finish basics.