In reply to Kemics:
youve not said if its a digital or film, compact, bridge, slr etc but I am going to assume its a dslr then you can check the shutter count
http://www.howtogeek.com/218244/how-to-check-a-dslrs-shutter-count-and-why-...
which will give you an idea of how used the body is, and regarding the lens, it would be good to have a receipt but not essential, Id rather have the boxes as its more likely to be genuine and not a stolen item.
I dont know how you intend to pay for it but please take care, cash on collection is good as you can check the item, otherwise Paypal (not friends / family) is safe as you can potentially claim back if they dont send the item, whereas if you do a bank transfer you are screwed ( been there done that
)
If its being posted, ensure they get it insured and tracked even if it means a few extra pounds to you, better safe than sorry.