Here's the deal, I am planning on doing a build very soon. I'm currently finalizing parts, I did initially plan on using HD2500 iGPU for a little while until I build up enough money for a 7850 or the likes. But, I have more money to spend on my build at the start then I anticipated. So, I looked around for a cheap GPU that will be able to play games (not on all high settings) and eventually settled on the 7750. 

This then put me in a bit of a dilema, do I go with the 2GB GDDR3 model and save a few ~£8 or spend the extra £s and get a 1GB GDDR5? 

I plan on using the card for more casual gaming at the moment: World of Tanks, maybe a little bit of Battlefield, Company of Heroes 2. 

Depends on your monitors resolution. 1080p or less, go for the 1GB GDDR5 for higher memory speed.

I think my monitor only goes up to 1080p

In that case, go for the 1GB version.

there is no 7xxx series card with GDDR3

Someone beat me to it, if it sayings anything other than GDDR5 it's a typo.

GDDR5 ram is normal ddr3 just with an 8 bit lookahead bus, just so you know. imo, go with the 2gb version. its a type, all gpus use gddr5