Hi Mez, my Natalie is similar - will go down without a problem during the day, but the overnight sleep is more difficult. She needs extra reassurance.
We too have a bit of a routine, which includes a story. Then I put her in bed and pat her bottom until she seems really sleepy (this doesn't take long - a few minutes). I give her a cuddly toy and leave. Sometimes she cries straight away and sits up in bed. So I go back in and pat, then leave again. I repeat until she stops crying, or only calls out when I leave the room.
It is hard when you have guests, I do understand. Is Natalie soothed by patting? My Natalie finds it even harder if I pick her up, you see, so it is better for both of us if she stays in the cot. Though I do understand this isn't the same for all babies... In fact only a couple of months ago my Natalie would've screamed at me if I had've tried patting her in the cot
They change all the time.