As long as its the same address should be fine.Emails to each other,letters,photos,council tax,everything that you can think of

 

IF it's a partner ship, based on what I've read, you need to submit documentation to support this partnership, i.e. preferably bank statements in both names, so we're talking of joint accounts here, even if it's just one account. Then if you have a joint account, you can also get your bank's branch manager to write a certification letter to support the bank statements. Utility bills are not really in two names, only one, but if you can have a bill in both your names, then that will help as well. The key here is, if you were processing the application, would you think 2 people with documentation in both names would seem more like a couple as compared to 2 people with separate documentation? Coz the latter explanation can be viewed as 2 people who decided they are "a couple" so they can use the system. I'm not saying you're not a couple, but I'm just looking at it from the Home OFfice's point of view, whcih is really how you should think, since they will be the ones processing your paperwork. It's always the proof that matters.

 

Same address should be sufficient,joint bills would be helpfull but not "compulsory"

 

If you have letters fom your mother,emails to each other,party ,new year photos,birthday cards,all the little things.They are more intrested to establish whether you are genuine couple rather then which one of you is paying water and electricity bills.
Certanly, include all the bank statments,accomodation contract,payslips,contract of employment,council tax,TV licence and bills that put you 2 together.