The DPF clears by running at higher temperatures (by burning more fuel, so MPG drops too) for a decent distance at a reasonable speed; it's more to do with how long not how fast so although the burning smell in traffic is indicative of the DPF regeneration cycle occurring, it might not be long enough to complete it hence the need to go for a run.
Give it a steady run at road speeds for 30 minutes or more and see if that clears it up.
But my journey doesn't last 30 mins or more. Thats the problem. I haven't had a warning light come on or anything. I have read that when the light come on (if ever) you can clear it by going on a long run. We did go out last night for a good 40 mins drive, which probably did it good.
So - do you think i should still to my normal driving style, by working up the gears to 6th gear and not giving it any welly.