After spending a while researching which components to get for my new PC, I've narrowed it down to the following.  
 
Bearing in mind, I'll be using it for gaming and I'd also like to have a go at OCing, but not to the extreme.  
 
Here's what I've got so far:
 
Intel Core 2 Duo E8400 £136
GA-P35-S3G £52 or [URL="http://www.ebuyer.com/product/136363"]GA
 
-P35-DS3[/URL] £63
Inno3D 8800GT 512MB £112 or  
 
Inno3D 8800GT 512MB Wind Edition Cooler £122 or  
 
Inno3D 8800GT OC edition 512MB £132
Corsair 4GB Kit DDR2 800MHz CL4(4-4-4-12) £70
Seagate 500GB 32MB Cache £54
Samsung SH-S203D 20X DVD±RW/RAM/DL £16
Coolermaster Elite 330 Case With CM eXtreme Power 460W PSU £44
Extra Value 120mm Blue LED Fan £2
 
I'd appreciate your thoughts and any changes you think I should make.
 
A few questions:
 
1. Would the GA-P35-S3G be sufficient for my overclocking needs?
2. Is the PSU good enough for this setup?
3. Would everything fit in the case ok?
4. Is there anything I'm missing or some other things I should consider, which I have not mentioned?
 
Many thanks for your help

Yes, the GA-P35 is fine for overclocking. The PSU doesn't look like anything special (>70% efficiency) but I don't know cause I've never used one. One suggestion: look into getting the 8800GTS 512mb instead of the GT since it has better cooling, is usually quieter, and costs only a little more. Just make sure it's the 512mb version and not the 640 or 320.

I would grab a Corsair PSU, probably the 550 VX.
 
Everything else looks great.

The Corsair PSU would be a great choice (VX 450W might be enough too).
 
8800GTS would be a better choice noise/performance wise but it costs quite a bit more in the UK from what I've seen.
This model is quite cheap :
http://www.ebuyer.com/product/142644
Inno model :
http://www.ebuyer.com/product/138551
 
The 120mm extra fan is a very good idea. The case you picked doesn't have a front intake (hard disk drive cage) fan.