Congratulations!
Don't disturb the mother too much, not too much noise or looking in at them, as they can eat their young if they are threatened. It happened to ours when we were children and had a rabbit who had young..wasn't very nice..
but yes, lots of food for mum, and warmth, especially this time of year. we used to tack an old thick blanket to the top of our hutch, to cover the grille when it was cold or wet when we kept them outside.
What are you going to do with the babies when they are grown, you will have to separate them quicker this time! You would need to start thinking about homes for them soon, rabbits are amazing house pets if you start them litter training etc young, and cover all the electric cables with hosepipe...
They will need vaccines etc, Mixi and another one I think, been a while since we had our house bunny.
So cute too, very jealous, can't wait to get DD a rabbit when she is old enough.
Good luck!