While I agree in part to some of your sentiments (I think he will be found guilty of sexual misconduct in Sweden, but I suspect he behaved in a way that many men do in countries without strong anti-rape laws), I absolutely disagree with your assertion that the UK government has any obligation to "hand him over" to anyone.
Irrespective of peoples' views of Assange and/or his actions, none of the players (Sweden, US, UK, Australia) has acted in a way conducive to believing they have transparently honourable intentions. In fact, Sweden has refused to deny they will hand him over to the US; the UK has threatened to remove the Ecuadoran embassy's status in order to remove Assange forcibly; the US has refused to deny they will charge him; Australia has essentially washed their hands of him, irrespective of his fate (we have had an Australian citizen, David Hicks, who was detained for 3 years at Guantanamo Bay *without charges*, in conditions the International Red Cross defines as "torture").
I don't care what people are accused of doing, we need to formally charge them and care for them in a humane way until their guilt or innocence is determined in an unbiased judicial procedure.