My pleasure Isa.
There's a chance it wasn't the soil. What specifically were the problems you were having with the herbs? They tend to do fine in even poor soil.
I'm not sure what brands are available in your area. If you can find them, here are some to look for:
Scotts compost-based mix
even Miracle Grow
Or go to your favorite nursery or greenhouse where you trust the people and ask. More than anything I would look for texture. There are a lot of soils out there that have bark and other "hard things" like charcoal, styrofoam, etc mixed in, in a word, lumpy. I personally do not prefer them but that's not to say they aren't effective. As I posted above, I like them light and fluffy (like a pillow to lay your head down on) or, like a genoise! LOL! So that when you pick up the huge bag, you're suprised at how light it really is.
The best "soil" actually doesn't have any "soil" in it!
Another option is to get the following inexpensive "ingredients": combine two parts peat moss (or well-de-composed compost), one part vermiculite and one part perlite. Then blend thoroughly. Nurseries should have these in stock and you should be able to buy just enough for your needs.
The reason it's so important is because it's like using real vanilla bean versus imitation vanilla extract. Get the good stuff because it makes a difference. I learned this myself the hard way. Had been gardening for years and didn't know the difference until one year I decided to try a good bag of "soil" which was actually a "soiless mix". The same plants I'd been growing for years grew to twice the size that year! I've never gone back and my plants are much happier.
Hummm.... my advice would be to purchase a 20 - 40 pound bag, you can repot all your plants and have soil on reserve in case they outgrow the pot or you decide to acquire more plants and you need more soil later. I do believe you get what you pay for. In this case, in the states, if your're spending $10-$15 on a 40 pound bag of soil, it's probably pretty good so you'd have to convert the currency...
If you ever want to browse on the subject, the
Soil, Compost and Mulch
Forum at GardenWeb is a great place.
Another tip, once you get your plants in good "soil", mulch your pots so the water doesn't evaporate so quickly as it often does with containers. It's less watering work for you and the plants aren't in complete danger of drying out.
Hope that helps, let us know how it goes!