Shopping bills (Within the UK)

I just conducted a small experiment. I usually shop from Tesco. I like to buy a large amount of things that will last me at least a couple of weeks. But now that I'm eating healthy, I'm finding it hard sticking to my budget. So today, I had two windows open. On one, I shopped in the sections with offers and such, buying what was cheap. It included pizza, chips, microwavable meals, tins of pasta and beans, stuff you can cook quickly. I was able to get 2 weeks worth of food for £35.65. I closed that window, as I no longer eat things like this.
On the other window, I was shopping for healthier food. I opted for fresh vegetables, noodles, ingredients for pasta bakes (they usually last me 3 days), brown rice, ingredients for vegetarian curry, free range eggs, and healthier versions of things like yoghurt and milk. I was able to get 2 weeks worth of food for £42.35.

Now, I understand that Tesco isn't the cheapest place to shop, but I've had some terrible experiences with Asda before and I'm not sure who else delivers. I'm a student, so I'm always desperately seeking for a bargain. So what I would like to ask is, where can I buy healthier food for a reasonable price? Where do you guys shop? Would you recommend them?