The 5x is the newer model so not sure if you'll get one for that price but the 5 will do everything you require and is currently running the latest version of Android, Marshmallow and should get "N" once it's rolled out to the newer Nexus devices.
personally I would consider the Galaxy A3 and J5
Great choice of starting phone.Thanks for the all the info and offers.
Ended up getting a secondhand Red Nexus 5 for £110. Very impressed. Getting used to Marshmallow over Jellybean, but so much better.
Battery life is still a disappointment, having to charge daily but I guess that is modern 'mobile' phones for you.