Room Divider - width between bars?

I'm looking at getting a room divider for my kitchen/diner so that we can have the back door open in the summer without having to get the rabbit pen out. I think it'll be so much nicer for them and much more practical to keep the whole dining room as their space rather than me putting them in the pen when we're using the garden/back door. I want a dark wood one ideally as it will look better with the furniture in the room and have been looking at http://www.orvis.co.uk/p/panel-zig-zag-dog-gates/8g35 which seems ideal (apart from the price :shock- the right colour and size but it says the gaps between the spindles is 1 3/4"
I'm not too worried about Rusty as he's pretty chunky but Pippa is quite small, she only weighs 1kg and tends to try and squash herself into small spaces. Is that gap going to be too big? What's the max gap size that's safe, searching online it seems to vary between 1.5 - 3" so I don't know what to rely on.
Any other suggestions for room dividers? As I said I ideally want dark wood and would prefer not to spend more than £150, £200 is my absolute max.

I'd be worried about them chewing through it, and the wood may not be rabbit safe wood. I've seen people use metal puppy pens for room dividers, or some people have had wooden framed panels made with Perspex in them. You might find inspiration in the housing sticky.

I'm a bit paranoid but I'd be worried about predators getting in with the door open.

Hadn't actually thought about the chewing, mine aren't really chewers, there's not a bit mark on their hidey house but wouldn't want to risk it
Not worried about predators though, our garden is the size of a postage stamp and the door would only be open if we were sat in the garden next to the back door or sat at the dining table in the rabbit's side of the room. Would close the back door if I was going upstairs/out of the room as we have had foxes around at night before so wouldn't take any chances
Have been browsing threads and seen the Manor Pet Housing pens with the perspex panels which look good, might ask about a room divider with those panels, at least I know it will be safe if they decide to start chewing, and I can use a pet safe stain so it matches the rest of the furniture.
Thanks

i got mine from kiddicare but its metal and it can go at different angle or straight, plus you can buy add on sections for it too