I'm finding it really hard to narrow it down!
Normal books:
How The Grinch Stole Christmas (will arrive with pjs on Xmas eve)
Possibly a couple of others by Seuss as DD loves them.
Some chapter books for DD(6) - possibly Roald Dahl/Enid Blyton... I work in a library so am in a way reluctant to buy many but then I adored having my own copies as a child too and maybe when I have read them to her she will also want to read them herself one day.
Picture books for DS(4) - a few Julia Donaldson ones we haven't got yet but we've had them from the library: superworm, stick man etc.
Other picture books we've enjoyed from the library. Some of which are my old favourites too :o
Possibly famous five annual for me 
Activity books:
DD - art (last term's topic) colouring especially Van Gogh as he's her favourite, titanic stickers (this term's topic), maybe Egypt (as they are getting playmobil pyramid), maze book, kings and queens stickers she can do with my mum (history nut)
DS - not so much into colouring so probably just a sticker book, maybe spaceships or dinosaurs. Possibly a really simple maze/tracing type book as he's just got into actually using a pen to write and draw (just started reception)
DH - M C Escher (favourite artist) colouring book :o
Me - some other artist colouring/doodle book, not decided yet.
Now to narrow it down
