Need any ideas for meals I can prepare for work in advance?

Not sure if this is the right subreddit for this but;

I'm trying to eat a bit healthier now since I started full time work in my office (and hopefully save a bit of money aswell) I usually eat in the canteen were a burger and chips is £2 but it isn't exactly the healthiest of options.

I need some ideas for meals I can prepare in advance, and the only thing I make is Pasta and tuna with some mayonaise and sweetcorn or bacon.

I have access to a microwave and constant boiling water.

Any ideas are welcome, the easier the better :D

bon appetit