To my knowledge, the only Police ASU using NVG in UK is the Devon and Cornwall one - they are still on an extended 'trial' I believe, having negotiated the need for goggles with the CAA.
Since the introduction of our FLIR/TV turret onto RAF SAR Sea Kings we are doing a lot more high hovering during searches whilst the RadOp uses the FLIR, typically at 1000' over land or water. The main requirement is a visual horizon, with that you can select a hover attitude and then use either doppler or visual markers to assess and correct any drift. One could hover on instruments but that is outside our release to service - if the weather is that bad the FLIR probably won't be much use anyway. NVG help enormously to give a good visual picture to hover on and the AFCS again makes things easier. We can use either rad alt hold or bar alt hold on the Mk3A but not the Mk3 - if it is turbulent the height hold can become a liability as it is not as quick to respond as a human left arm. Good crew cooperation and communication is also essential with the NHP monitoring RoD.
Can it be done without all the gucci kit? yes of course, as helidriver says but tales of disorientation, LTE and VRS abound amongst the crews who have done it - having the right kit to do the job makes it so much less stressfull.