We need to know more than anything else how many passengers you want to take. Presumably there are quite a few children.
Rovaniemi in Finland is the No 1 destination for charters to Lapland (the Arctic Circle line passes through the terminal and is marked on the floor). The flight there is about 3.5 hours from London, so 7 hours round trip. Pretty much the same as the Canaries.
A 150 seat charter 737-800 or A320 normally costs the charterer about £30k for the aircraft round trip, day return with time to see Rovaniemi (which in all honesty does not take long). So £200 a seat cost. Commercial operators charge you notably more, they have their own costs and profit, plus the risk of not selling all seats, promo seats given away free, etc.
There is spare capacity in the UK charter market in November/early December which is why the Lapland flights are relatively cheap. The aircraft used at weekends will be redeployed in a few weeks time once the skiing season starts to the Alps.
If you are going to Lapland at this time of year do not forget (as quite a number do) that it is completely dark up there 24 hours a day, so you will not see any views.