The blue circe is GPRS, which is the slowest form of mobile internet. On the iphone you get that with poor receptions areas, then you get E for edge mobile internet and on the 3G devices you get 3G when you are in 3G mobile internet areas.
According to Vodafone Cardiff has 3g coverage
Mobile Phone Coverage UK - Vodafone
So it is a bit of a mystery why your are crawling along on GPRS. As you have mobile internet it is working, are you sure your mobile account with Vodafone covers 3g Mobile internet? If it does then I suppose the only other issue is your unlock with the Turbosim and I have no experience with those so I can't help there.