Buy a bunch of these, and sling them on your tactical marines' waists:
https://www.forgeworld.co.uk/en-GB/Chain-Axes
It's definitely a start, and you'll want to use basically everything in the
BAC box - the box itself contains somewhere in the region of 1000pts, if I recall? You could definitely start playing Zone Mortalis, etc. with that sized of army.
Full-sized games of 30K tend to be around 3000pts, and
BAC + Angron will be about 1500ptsish? From there, the world's your oyster and you could get Legion Specific Terminators, a Spartan Assault Tank to send Angron forward in, some air support like a Lightning, Storm Eagle or Fire Raptor. You'll definitely want a bunch of anti-tank in there as well.
As long as you pick up some chainaxes, there's no reason you don't have enough to get started painting and playing though.