as the title really guys looking at a new laptop must be powerfull enough for photo editing using Photoshop and streaming video dont wish to pay more than £400 really

Just bought the daughter an A8 HP laptop with 8GB RAM, Win8.1 and touchscreen; was about 450 from Currys. If you're not worried about the touchscreen, I'm sure you'll find the a similar model without it for around the 400 mark...

Will be more than powerful for what you want to do; just make sure it has *at least* 8GB of RAM if you're wanting to do photo editing.

Just got my daughter one of these at 229

http://www.currys.co.uk/gbuk/computing/laptops/laptops/lenovo-g50-30-15-6-laptop-black-10022697-pdt.html

Would be good for what you want, but the keyboard feels very flimsy so may be worth paying a bit more for better quality.
Regards
Hugh