Hi there and welcome 🙂
As you are married you may well be entitled to a portion of her assets, this may include some of the mortgage contributions you have paid and you should talk to the solicitor about this.
Its not easy finding rental property and you have to be on the ball and be very quick. Getting hold of the deposit can be a headache too, my daughter moved recently and I had to help with hers as it was over £!000. Perhaps you should talk to your wife and tell her that if she wants you out you will need financial assistance with the deposit, otherwise you will be unable to leave.
As far as maintenance for your boy is concerned, what she earns has no bearing on what you pay...its all to do with the amount you earn. If you google CSA calculator it will take you to a page where you can input your details and get an estimate of what you will be liable for. It might be that she will agree to a family based arrangement but if you go along with this make sure that whatever payment you make is recorded as "maintenance payment for (name of child)" and dated and signed. The best way to do this would be through a standing order as you will be able to have that as the reference.
There is a very informative sticky at the top of the Finance section called "How does the CSA calculate payments". if you follow the link it opens a CSA leaflet that you may find useful.
It might be a good idea to get contact with your son sorted before you agree to move too. Ask your wife to sit down with you to discuss the days and times you can have access. Try and include weekend stay overs with you after you have moved, and extra blocks of time in the school holidays. You could suggest that Christmas and birthdays be shared, maybe taking turns...one year you have him and the next year it would be her turn. If you can get a written and signed agreement from her before you agree to move it would be helpful. Although I dont think its a totally binding agreement, if you had to go to court over contact in the future it will be a helpful benchmark.
In the meantime try to keep everything on an even keel and avoid all arguements and confrontational situations, it has been known for some women to use arguements etc to call the police and get their estranged partners removed and you might end up with anything from an injunction, non-molestation order, harassment or worse....this could then be used against you as far as access to your child is concerned. She may not do this but its better to be aware!
If you feel that you cannot sit down with her and talk things through you could try Mediation as a way forward. Heres a link ~
www.nfm.org.uk
To look for a mediation service in your area there is a sticky at the top of the Legal Eagle section called "Looking for Mediation in your area?"
Best of Luck with it all, you have a stressful time ahead of you but once everything is concluded things will settle and you will start to feel better. 🙂