well, in the end i went for the first wing of BRM and did two arenas.
the first (the free one) didn't go that well as i didn't know what i was doing and i only managed to get 2 wins, got packet and 50g.
so i looked at an arena guide before doing another one.
the second one went better as i managed to get 5 wins (could have been more as i lost a close match after losing a turn due to a disconnection), got packet, 60g and 55d.
probably beginner's luck but i think i will continue with arenas until i regequit after losing 0/3 twice or thrice in a row.
the only thing that bugs me is that you can only get GvG packs this way, really stupid in my opinion, they should give a coupon for a pack instead.