Hi. No it won't bottleneck your GPU. 1GB is fine but having 2GB wouldn't hurt for future games or monitor upgrade if you can afford it. But you should get either the GTX 660 for £5 more or HD 7870 for £10 more from Amazon instead of the HD 7850 2GB.
The "little" dual core i3-3220 w/HT is an amazing gaming processor for its cost. It will handle just about any GFX card you want to use with very little or no 'bottleneck'. At 1600x1200, the 1GB will probably be sufficient. But I would opt for the 2GB anyway.
(I put that 2GB card in a stock PH II X4 965BE, and it ran any game I tried at 1920x1080 at max settings.)
It all depends on how much 'bottle neck' one feels is detrimental. If it can run the game at the required resolution and get fast frame rates with max/near max settings, a small amount of bottle neck isn't an issue. If you can't see it, it ain't there.
One PC with i3 3220 will have lower FPS then the same pc with an i5 3570k. SO, the CPU will hold you back a little and you can call it a bottleneck. The true question is : "will an i3 3220 reduce the performance of the 7850 to an unplayable FPS?" the answer is : "no, you will be fine, the i3 /hd7850 combo will play any modern game @ medium/high/ultra depending the resolution and the ammount of MXAA"
no, an i3-3220 is faster than a q6600 at everything. 2 cores with hyperthreading can do the work of 4 cores.
2 HT cores are lesser than two actual physical cores. That is why HT is added. With 5-10% increase in die area, you get ~30% performance increase.. Caveat : the application should benefit from HT. This means, it has lots of memory-toCPU copying on one thread, during which the other thread can do CPU work. If the application has interleaved memory access, HT will give no benefit. Plus, cache is shared between real and the HT core. So if one thread has lots of cache thrashing, the other thread will keep waiting for execution. And the overall cache is effectively halved between the two threads.
Regarding this particular case, you could possibly be correct. I have no data off-hand to back my claim.