I'm slightly confused by some of the answers to this post where people say the police had no other option at the time - it is my understanding that issues of property ownership like this, and trespass in particular, fall under Civil Law rather than Criminal Law. Though the Criminal Justice and Public Order Act 1994 did expand the polices powers to remove squatters in some situations I do not think these apply in this case. Therefore the Police should not have threatened anyone with arrest and you should take the matter forward as they basically threw you out of your own home.
It is the Police authorities Professional Standards departments that investigate complaints - select the relevant authorities contact details here:
http://www.ipcc.gov.u..._contact_details.aspx
I think you should ask as a goodwill gesture for a reimbursement for the hotel bill for being threatened with arrest if you didn't leave your house... which I think is a really big / scary thing to have had to deal with and should be recognised as such.