Funny, I find MX3 to be OK especially the red shrimp noodle one.
For Mountian House, another vote for pasta bog, for cheapest MH prices use "beyond the beaten track" for all other use outdoors grub. Real Turmat sounds good but £9.00 a pop seems crazy!
agree with the mob, any idiot can use a bivi tarp an be uncomfotable!
I use a tarp tent which is bombproof and unless weather is really bad I tend to sleep with outer door open. I love the idea of bivi/tarp but in all but perfect conditions can't get on with it.
Have a look at the mini peak tents at backpacking light, I don't have one but think they might be a good cheap tent/tarp option for the spring/summer.
I'd second hydration, take a few nuuns to drop in your water.
I also graze but with more protein eg almonds and jerky. Jaffa cakes are very good as a reasonably balanced energy source however I don't have the will power and on a multiday trek they disappear very quickly during the first day
Decent quality easily accessible protein within 20 mins of finishing walking for the day can help prevent next day muscle stiffness/soreness aswell.