Some reasons why a wifi network that is reported as "unsecured" might not connect:
1) The wifi access point operates a list of permitted MAC numbers. A MAC is a worldwide-unique number which every network adaptor has, and your laptop's wifi module will have one. You need to get your MAC number added to the whitelist. This is a rather crude security measure but it is popular because it has no impact on equipment compatibility.
2) No DHCP server available. Most access points have a DHCP server behind them somewhere, which will issue an IP to you. If this isn't the case, you will have to find out which IP (or IP range) your laptop needs to be configured to (under TCP/IP). This kind of measure is not unusual in serious corporate networks.
3) Has DHCP but the client limit has been exhausted. If you know you have a max of 3 laptops, you can set a DHCP server to issue say a max of 3 IPs. The 4th person isn't going to get connected. This is a crude security measure but is popular because again has no effect on compatibility.
4) Some weird incompatibility. Wifi has (and has had) plenty of those. Wait till you get onto Bluetooth
5) In your case, it might appear that the access point in question is a public use one so should work but this may not be the case. Nowadays, the vast majority of networks one can pick up are not for public use.
There is just one way to get reliable connectivity: GRPS/3G. I use this 95% of the time, because most wifi network owners have wisened up to either leaching or the opportunity to make money. Most places I've been to I can't get a connection where I really need it. Do an Ebay search on Vodafone Mobile Connect.