The R9 380 can also be had for under £150, a bit quicker than the 960. Both will only have 2GB of vram at that price.
http://www.ebuyer.com/714714-sapphir...e-11242-02-20g
Edit to add:
TBH, I am not sure which of the two I would go for they are fairly evenly matched. When I made my decision there was a clear price advantage as the 960 was stupidly overpriced.
Thoughts of getting a freesync monitor in the future did play a part in going AMD.
For your current 720p requirement, either would give really high frame rates with the quality turned quite high up.