I picked up the Hobby range from here
for about £100. I don't know how well that would factor in for postage to France but it's enough of a discount it may be worth sending them an e-mail over; especially with the direction the exchange rate is headed.
From the sounds of it, you'd be better suited to the Military set because it would provide the colours worth it to your army. The guys who run the website are fairly flexible though - I already had a few Vallejo paints and when I placed my order for the set they were able to swap out any duplicates for other paints I wanted. So it's perfectly possible to send them an e-mail to see if they'd do the same and swap out any shades that you don't need in favour of ones that you do. If you paint a lot of metals I'd suggest getting the metal medium, which is excellent for that final layer of highlight. It's a good shade or three lighter than mithril silver.
I'd definitely advise model over game ranges when it comes to buying sets. Model simply has a much wider variety of shades, and is of finer quality pigment. I find it paints beautifully. That said there's no need to exclude Game range because they're all acrylic so it's perfectly easy to mix them to find the colours you want.
Model range has a finer pigment and more variety of colours but it's less durable, so until it's had a good 24 hours to set you want to be careful when handling the model, and varnishing is definitely advised.
Game range has less range of colours, but it's formula is designed to be a little more durable to handling with gamers in mind, which is why a lot of it's colours are comparable in shade to GW ones (Warlord Purple? Hang on a minute ...)
I use model range because most of the painting I do with them aren't for gaming pieces but more for display ones. Even if you are using gaming pieces you won't notice much difference once it's all been varnished (which, if you take care over your painting and are taking them onto the battlefield, I assume you'll be doing.)
As for whether or not it's worth making the switch from GW paints, Vallejo are better quality, in bigger pots (17ml versus 12ml), have a wider range and cost less. I'd consider it a bit of a no brainer, personally. Also as I mentioned they're all acrylic (apart from the Liquid Gold range) so you can still use them in conjunction with your remaining GW paints.