To be pedantic, you're not receiving Freeview at all.
Freeview is an entirely terrestrial service, which is completely separate from FreeSat, Freesat-from-Sky, or (service free) 'Free to Air' reception. The digital switchover only affects terrestrial TV; it will have no effect whatsoever upon reception via a Sky box (irrespective of where you've got a Sky subscription or not).
With a Sky subscription the regional TV services you receive are determined by your postcode. Without a subscription you're simply receiving the 'FTA' (Free to Air) channels and you might find that you receive TV from a different region (probably London). To get your own region back you'll have to enter the manual tuning settings, using the information in the last column here:
http://en.wikipedia.o...channels_at_28%C2%B0E
(Under 'Regional').
Chris