In my opinion, there are a lot of better alternatives on that website.
The ASG P09 has had very good reviews. However beware: there are two versions - one with all polymer externals and the more expensive one with polymer lower and metal slide. The latter version is very popular and will take both green gas and CO2. The all plastic one won't.
The P09 will probably come with a green gas magazine and you will have to buy a separate CO2 mag if you want that. Recoil and velocity with CO2 will be impressive, but bear in mind that the higher pressure of this gas will put the internals of the gun under greater strain and wear things out faster. The P09 is made by KJW incidentally.
Then there are some KJW own brand all metal guns, and I believe some of the ASG Colts and Berettas are made by KJW too. You will need to do some research. Most KJW all metal guns will take both green gas and CO2. Both types of magazines are available.
I would not advise you to get WE because, although their guns are better than KWC in my opinion, you have stated that you want a CO2 gun because of the low Swedish temperature. Not all WE pistols are CO2 compatible, and even for the ones that are, availability of mags is sometimes poor.
Perhaps somebody else (a more experienced member than me) on the forum could chime in and give their two cents' worth. There are plenty of pistols on the site and the lad is looking for advice. What would the rest of you suggest?.
I would certainly consider the following, but go to the shop, ask questions and get the feel of them.
http://www.rodastjarnan.com/airsoft/kjw-asg-gbb-m9-heavy-weight-18036
http://www.rodastjarnan.com/airsoft/kjw-asg-gbb-m9-ia-heavy-weight-17947
http://www.rodastjarnan.com/airsoft/secutor-rudis-1911-svart-gbb/co2-37721
http://www.rodastjarnan.com/airsoft/secutor-rudis-ii-1911-svart-gbb/co2-37727
I believe the Rudis 1911s are made by WE but they are CO2.
I think the this is a KJW built gun, and the black one of similar price.
http://www.rodastjarnan.com/airsoft/asg-dan-wesson-valor-co2-gbb-36385
But don't take my word for anything. I am not an expert. Research, and then go and look at a couple in the shop if you can.
Avoid anything by APS.