Is the Air Asia ticket cheap enough to buy both?

If BA is on time you'll make it - you may need to take a short shuttle train to the main terminal, then it's security at the Phuket gate itself. No passing any transit checks- departure and arrivals are mixed.

Air Asia necessitates a transfer to KLIA 2 which I noticed last week seems to now be possible airside by a shuttle bus (presumably without clearing immigration, which is good news as it can be very slow!)

**sorry I had read 40mins!, 1hr 40 no problem. Realistically if you've missed that you wouldn't make the Air Asia anyway so I wouldn't bother**