Their official line will always be no, even if you are simply moving across the channel to Calais.
In real terms, there are tens, possibly hundreds of thousands of
Sky subscribers living and viewing outside the UK.
If you can maintain a UK address via a relative as a billing address, then you simply take your box abroad with you, what you do have to do though, is put up a big enough dish to receive the channels you require.
If you also require to watch channels on Astra 2D, like BBC and ITV, you will need a large dish, probably in excess of 2.0m (sky sports active also on this beam at the moment), for the rest, probably a 1.2m dish will suffice.