Good news from my physio today, he scanned my ankle and all my ligaments are intact, no tears, just a bit of fluid. Was pleased to hear i still have an ATFL too (apprently it's pretty common to tear this completely and still have a functional ankle).
Apparently its a grade 1 sprain so with rehab i should be back on the board in 2 weeks and more or less fully healed in 3-4 weeks. Good news all round really.
I had the brace conversation with him, and his general advice was to wear ankle braces when skating (in my case), apparently having lax ankle ligaments means i'm less likely to tear them, but more likely to roll my ankle in the first place - which is what i suspected. He said that as far as prevention goes, most NBA players tape or brace their ankles for games, so there must be something to it.
He said you could do all the ankle strengthening and prehab/rehab in the world, but if you land wrong then there's always the possibility of an ankle roll due to sheer physics, it's pretty impossible to take it out of skating as risk, so bracing is a sensible next best thing alongside a decent amount of rehab folling a sprain.