Re: Creepy
So should it be:
A) "Now we have been working together for a several months, I realise that you are the kind of person I like & get on really well with. We have a few interests in common and we have talked loads while working on projects together. Unfortunately seeing as we work together I feel that we cannot be friends so, thanks for the invite to your housewarming/BBQ/Social event but no, don't ask again."
Or
B) "How was my weekend? What has that got to do with work? We are at work and you are only a colleague so please keep any discussion to work topics only?"
Maybe, just see how you get on with the people you work with, find out that out of all of them there are 1 or 2 that you wouldn't mind socialising with outside of work & gradually transition from colleagues into friends.
Caveat... If the only people you have as friends are from work then maybe look at socialising more.