Thanks everyone for your replies - you guys are great!!!
As for trying one elimination thing at a time, ideally I would, but well, I'm a bit impatient.

I'm going to eliminate both, see if it helps, then reintroduce lactose and/or wheat one thing at a time and see if it causes the bloating to come back. I'm certainly not going to leave them out of my diet if the bloating doesn't improve - I'm not really one to advocate cutting entire food groups out for no reason!
This tummy thing really has me at a bit of a loss, I suspect a lot of it may be due to binging (and yes I have been continuing to get help to stay on top of my eating probs) and dumping so much bad food into my system at once
Sarah, I've been reading your journal over the past little while, even while i haven't been posting, and I really do sympathise with you - I know how awful it is, and I am amazed I haven't put on more weight from overeating so much!
Hey Milkyway, tri season has well and truly started and I am lovin' it!! To everyone else who has responded - thank you very much!!
Molli.