Is it not that food is just so cheap now? A little bit of tax won't make any difference - three or four times the current price of your average junk food might make fresh food more attractive and perhaps make people choose between fags and food.
I also think big cuts to NHS provisions are inevitable in the near future just as pensions and benefits have already been cut.
Hi Laura - the tip of monitoring your resting HR in the mornings is key - I've done this and it really is the best way to guage progress and stop you from overdoing things. Some really excellent advice from rowex and CheesyRider.