The i7-4710MQ is a laptop/mobile processor, and so is the i7-4800MQ. In addition, the Nvidia GTX 880M is also mobile graphics.
You can't upgrade graphics on a laptop/notebook, so I wouldn't worry about bottlenecking as your laptop manufacturer has already considered this. Even so, an i7 won't bottleneck anything as it's the best available at the moment.
With that said, the 4710MQ is quite a powerful CPU and NO, I would not pay £50 more for an i7-4800MQ; they both provide similar performance and you won't notice the additional performance gain from paying £50 more. I'd just save your money here.
All the best.