Ok. Right...
I'm going to address each problem you have separately, which is what I think you should do if of course you decide not to rehome her.

Ok. Right. Sounds like as you mentioned she came from an abusive home in the past. This girl has had a hard time. You need to get her to trust you. I don't know how you "tell her off" or what this involves. But if it involves shouting, smacking, tapping, leaning over her or simular, or talking to her in a firm voice even, I wouldn't do it. And tell your husband not to either. Her behaviour sounds to me (although you definately need to get a qualified BEHAVIOURIST to confirm this and see the dog) to be defensive, perhaps she has experienced this in the past and has learnt that the only way to get the people who do this to go away is by using aggression. Aggressive behaviour to a dog is a very risky thing to do, most dogs would choose to run away if possible from a fearful situation so your dog is obviously very uncomfortable or feels that there is no way of escaping.
With this dog you are going to need to make associations with all the people she has "issues with" positive and yourself too. Ignore the bad, reward the good. Maybe get your husband to be the one who feeds her every day, walk her with you too, plays with her etc... Obviously though as the dog has snapped/nipped, you are going to need to take extra precautions. Unsure your children and the dog are never left alone together (sorry if you already do this), ask the children to try and act calmly around her and explain the situation with her to them (the dog get's worried about things etc...), I'm sure your children will be very willing to listen and help

2. Where is the dog when this all happens? Is she indoors with you? I would get her a crate or a special bed/place and train her to go to that place on command and reward her with treats or toys (whatever motivates her). Maybe give her a stuffed kong to eat whilst you get the post etc... You need to make positive associations with the crate/place so that she knows that it is a good/fun place to go and not just somewhere where she gets locked away. If you do this right, it'll mean the dog has a retreat, where she can go during the day if she finds a situation too much. Perhaps the children are playing, she can sit in her bed/crate with a stuffed kong.

3. Ok. The crate would be a solution to this problem too. Although you need to make sure you crate train her correctly- so that she recognises it as a really positive place- not just somewhere she gets trapped. That way, if you are going out for an hour you can put her in the crate with a stuffed kong and some toys and water and she won't be able to be destructive. Sounds like she could have separation anxiety though, which would explain the chewing - she is doing it because she is stressed. In this case you need to build up the amount of time you leave her for- from 5 minutes with you in another room to 2 hours with her in her crate. This needs to be done gradually.

Now a few questions:

Is she walked? How often? How long for?
What is she fed on?


I can see how you are finding things hard work but please do not put her to sleep. That isn't fair. None of this is her fault.
If you do decide to rehome her, contact a reputable rescue centre preferably with experience of her breeds (I know she is a cross but I'm sure either lab or spaniel rescue would be happy to help you). What area of the country are you in? Someone may be able to advise a good rescue that is local to you.
If you do decide to keep her, you are going to need to commit to making changes and working with her. You should also contact your local behaviourist who will be able to help and advise you.
The APDT are really good:
Welcome to APDT - Association of Pet Dog Trainers UK

Check out your local behaviourist here:
Local Dog Trainers - Association of Pet Dog Trainers UK

I hope this helps you.
Please keep us updated

Edited to add:
Just saw that your are in Norfolk. Here is a list of APDT behaviourists in the region. I don't know whereabouts you are in the region but hopefully one is close to you.

Source for all of the above: http://www.apdt.co.uk/trainers_area.asp?area=Norfolk

With regards to rescues, here are a few Norfolk Rescues:
http://www.dogrescuenorfolk.com/
http://www.faithanimalrescue.co.uk/
http://www.care-uk.com/
http://www.nasatrust.co.uk/

Another place worth going for advice is
www.dogpages.org.uk
They have a forum there with loads of rescue representatives so if you contact a local rescue on there they may be able to give you some advice and if you do decide to rehome her, find a suitable home.

Hope all this helps. Best of luck

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