Take professional advice - pensions is a minefield!
Your pension has a PTV (Potential Transfer Value) which can be transferred to the Police pension scheme. This, however, is a financial value which will boost your police pension when it becomes payable. What does not transfer is the number of years of service. IE You cannot do 4 or 5 years in the Fuzz and retire with an immediate pension - you must fulfil the minimum requirement for their pension scheme (25 years I think or attainment of a certain age if this occurs earlier).
Alternatively you can choose not to transfer your service pension and that will become payable when you claim it at age 60 (asasuming you are not commissioned currently).
From a financial perspective your best option by far is to remain in the services until your 22 year point.
Transferred mine into the NHS when I joined it and got an extra three year's worth (Full NHS pension is a half final salary after 40 yes 40 years). As has been mentioned, see a financial advisor, 'cos it's a real minefield. The answer to the question, though, is yes, you can transfer it.