We've moved three times, were at one place 15 months, but when the person checking saw that, she said "I hope you have lots of documentation". Fortunately, everything was in both names, tenancy agreements, water bills, gas, electric. I believe I had more than 10 joint things for each year.
This was the thing they scrutinized most-
PS- I got it!!!!!!!
It helped to make a table, showing the various months of bills scattered throughout the two years. I couldn't wait to get out of that place- between the calling for people to get fingerprinted and the hassle they were giving some people, the pressure is intense. Plus, sigh, 500 pounds gone....
Thanks everyone for your great advice and help- it is so good to know what to expect.