I have a 'clucker'!

I would leave her to it. But closer to the time put steps or ramp up so chicks can get out of the nest box.
I would also wait for someone with more experience of broody chickens and chicks to give you advice.

Would the chicks be safe from the other hens and cockerel, do you think? When I hatched other chicks i fed them with 'Chick crumb' so would probaly need to supply some.The problems i could envisage would be how do I keep the others off it?

If her clutch is accessible to other chooks mark them with a couple of pencil X incase any of the other gals lay in there when she gets off for a poop/drink/nosh.
Check there are no new ones daily..if so remove them ( they'll still be edible even if sat on for a few hours)
Also, make sure you take her to the water/food at least once a day to make sure she stays hydrated etc.

It would be better if you can get your hands on a small bunny hutch to put in there for the duration to prevent additional eggs joining her clutch!

Just before the eggs are due to hatch she really needs to go into a box with a mesh front so she's not disturbed during the hatching...nor for the 1-2 days afterwards whilst she teaches them how to scratch and peck at chick crumb and drink from a small ramekin dish with about 1 cm of water in there ( yep..they can drown in that shallow water ..so add a few small pebbles in there too)

If the box has a mesh front then all the other gals and your cockerel will be used to seeing
/ hearing the chicks so when you open up the box the chicks won't be attacked by the others.
It is a worrying moment and you need to be with them, but we've never had the chicks attacked. The cockerel will go and take a close look and recognise them as part of his family group.

Mom needs to be able to access that box at all times and be locked away in there with them at night until the chicks are larger.
My box is something I made 1'x 1' x2' wide ( for banties) with a top hinged front mesh.

As SP suggests, the chicks will need to access the floor easily, and for mom to take the chicks away from the other hens during the day when they go under her wings for a kip..so it might be worth reviewing where they will stay.

Chick crumb...well I leave it in their box and scatter it around outside it so they learn to scratch.
Yup the others will eat some of it, but it's nothing to worry about as far as I have experienced....but mine do free range so they're eating grubs and insects and adult food within a few days!

Those are my initial thoughts/ experiences if they are of any help?

Chicks raised by mum are so much more clever than incubator chicks, healthier too because she teaches them to preen and what's good to eat.

Whenever we've hatched eggs (always with a broody) we've found that mum is very fierce in her defence of them from other birds...but we do keep them away from the others for a week or two, divided by mesh just to be safe.

If you've hatched before with an incubator you'll already know pretty much all you need to, mum will do the lions share of the work anyway!
A good broody will turn her eggs daily and will eject any 'iffy' ones (a rotten egg in the clutch can kill all the others) so if she chucks one out, never put it back unless you've candled it and seen the chick moving inside.

Hopefully the weather will improve before they hatch but it's worth being mindful of temps if, like me, you have a mixed flock. A dozen eggs is a lot for a bantam to sit on, the if some of them are full size and once hatched I found that not all the chicks could fit under my tiny bantam to keep warm! A three or four inch barrier round the side of the hutch to limit draughts makes a big difference! And if the weather is squally you may need to take them inside.

All chickens seem tp love chick crumb which is just as well since a single clutch will never finish a whole bag before moving on to growers. A greater risk is chicks getting hold of layers mash or pellets which is not at all good for them.

If I were you I'd start candling eggs when you turf mum out to eat and drink. Any not showing signs by the end of the week get rid of. Seven is a good number for a bantam to end up with. A few will be infertile from the get go, you might lose one or two as you go along. Every one lost gives the others a better chance unless you get down to below three (when she might abandon them).

So exciting!
I'm dead jealous! But promised myself never again because I always fall in love with the lads and I can't keep roosters in a London council estate back garden!