That wasn't intentional, more a result of my circumstances. I first put the computer together while I was at school, then through my 5 years of uni I didn't have any spare cash to put into it. Now that I'm working I'm finally in a position to make some upgrades. I don't plan on having a computer last as long as this one has with no changes in future!
On the GPU front I trawled eBay & other forums looking for used 2gb gtx 950s & 960s, the going rates for both looked to be about £130 - I'm sure you could find cheaper ones if you were patient & really hunted but since new 2gb 960s start about £150 I decided to check them out & eventually found an ex-display factory overclocked gtx 960 4gb for £150 (reduced from £180) so have gone with that. Considering it's only another £20 for a "new" card & extra 2gb I'm happy to pay the little extra plus resale should be higher if I'm looking to upgrade at the end of the year.
Thanks for the advise guys & steering me away from the 980 Ti, your help is much appreciated as always!