Hi Sophh,
I have also just found out that I'm expecting (only 4w/ks) I need to loose at least a stone and like you want to improve health. Usually I don't eat during the day, i just drink coffee and binge at night....Not anymore here's what I've been doing..
In the morning I eat when I start to get hungry and have some flavoured porridge which I eat cold...weird I know. I don't eat all of it. Alternativly Rye bread is yummy toasted with butter & jam!
OR if you prefer something hot go for poached eggs on toast!
The key here is NOT to eat complex carbs (anything like white bread/cereals)
I then have something protein based (like meat) roasted in some fajita mix with some roasted veg and eat until I'm full/comfortable.
By 3/4pm I'm ready to smash it at the gym and I run for 20 mintes. However since being pregnant my temperature is through the roof so I haven't been able to sustain this for very long. But if you don't have a gym membership, just do somthing....Anything then build yourselof up. You could start with cleaning/gardening.
For dinner I go for something Protein based again and pack it full of veg. If I'm feeling like a little 'treat' I'll have pasta/spaggetti but this is a complex carb and shouldn't be consumed too regularly unless you're doing crazy amounts of high impact exercise....
I love a good Latte too to top it off... Then to stop myself from binging on things that are bad in the evenings I have been repainting my home!
As long as you eat as much lean meats as you like, vegetables, fruit, pulses you should notice the difference in energy and how you feel.
I have also been drinking more squash, whereas before I only drank coffee.
One thing I would certainly reccommend is going on tesco recipes (I'm sure other supermarkets have them too) then I find a recipe I like the look of and add it to my basket! I hate cooking and I'm a busy lady so it's usually something dead simple.
Have fun and congrats