Can i buy Iphone se A1723 in UK on website?

It is available according to the tech specs at the UK site - http://www.apple.com/uk/iphone-se/specs/

However, I have no idea whether you are eligible to shop at the UK site - http://www.apple.com/uk/shop/help

Do you live in the UK? Do you have a street address for shipping to in the UK? Do you have a UK based method of payment with a UK billing address? If not all of those, then no, you cannot shop at the UK web store. Apple online stores require payment in local currency and they charge appropriate taxes based on your billing address in the country of the store you are shopping at. They also do not ship internationally, so you must have a valid shipping address within the country of the store you are shopping at.