How long do they lay for?

[sophiejw]

I've been on the hunt for some more chickens to add to my flock (it's been really hard to find anywhere local that I can buy birds from). Anyway I've been offered some Warrens- they are 18 months old and apparently good layers. Only £3 each too. What I'm wondering though is how long are they likely to lay for? I don't want them to stop laying completely when they hit 2 years, though I don't mind if egg laying reduces gradually over time. My two hybrids that I have are about 18 months old, and ideally I wanted younger birds so I don't have a lot all tailing off at once. But since it's been so hard to find any to buy I am tempted, Warrens are meant to be very good layers so could go down abit and still give a good amount of eggs (if that makes sense).
Any thoughts much appreciated