Pat is right for comfort go the D3 or L322 Range Rover. If I had the money at the time I would have bought Pat and Tracey's and got rid of the Defender.
Not entirely sure of your budget but sounds it may be at the lower end. The issue is for a TD5 110 you will still be looking at $20k plus for a decent one with a heap of accessories, maybe $15-$20 for a reasonable one. We are starting to see D3 around this price recently for V8s and around $25 for TD6.
Dont get me wrong we love the Defender, but it has some major short comings for a touring vehicle with a family of 5. It has been suggested you get a side seat vehicle. The downside of this is you lose the load space which it seems is what you are after. The other issue is side seat injuries in accidents are significantly worse due to the inertia.
I have tried to be as honest as possible, without criticizing the Defender too much. You will either love it or hate it.
As also said different seats are available from Exmoor trim, but by the time you land them here will be a couple of thousand dollars. Then when you fit them the cargo barrier must be moved back so will take some mods and a standard drawer system etc will not fit.
Your kids may love it.
With 3 kids if you decide to go the Defender path I would go a 130 with a tradesman body on the back. That is what I would do if I was going down this path again.
Ideally if you can get hold of one for a day or two and take your kids for a decent drive on a warm day, this may answer a few questions for you.
If you let us know a ball park figure what your budget is it may help and if you have a budget for accessories.
The link below has a few for sale in WA and may help your search. There is a nice red TD5, a white Puma and a couple of others. If you scroll down a fair way there is a decent optioned up TD5 green, similar to mine, but IMHO he wnats too much for it and he will probablly keep it.
https://www.facebook.com/groups/1455848934628316/

