High End Video Editing Laptop <£1500

Hello!

First of all thanks for taking the time to go through this thread.

I'm looking to buy a new laptop, I am an animator and I will need to use Adobe products such as premier, photoshop and after effects. I am adverse to buying a macbook pro retina so have found a website where I can customize everything.

Basically I would like to know if http/www.pcspecialist.co.uk/ make good quality builds?

And secondly, how are these specs? Considering the price is £1250, £800 less than the 15 inch retina.

15.6 Matte Full HD IPS LED Widescreen 1920x1080
Intel Core i7-4800MQ (2.70GHz) 6MB
16GB Kingston Hyper-X Genesis 1600MHz (2x8GB)
NVIDIA GeForce GTX 850M
500GB Samsung 840 SSD
1TB WD Scorpio Blue

I am assuming that all the programmes will run, does anyone know about the quality of the screen compared to the retina?

The final point would be on their website they say that it uses a 6 Cell Lithium Ion Batter (48.84WH) but that it only lasts between 1.5 and 3 hours. How difficult would it be to increase the battery life? Would I be able to buy a battery with more cells?

Thank you so much!