I would go for a 100/0
80/20 split on the property on the basis that you will be the primary carer for your dc and settling the dc into daycare and returning to work will leave you with little time to househunt and moving will be disruptive to your newly established routine and you may need to find another nursery/childminder if you can't afford to buy in the same area etc.
Depending on your individual circumstances, you could set your baseline at 70/30 but always ask for more than you're prepared to accept as you might get it and, if not, you'll have some haggling room which can be used to make the other side believe that they've scored the winning goal instead of an own goal. 
Please note that the above is not to suggest that you shouldn't wing your plan to remain in marital home until your dc is 18 by whichever solicitor you consult.
Regardless of what your h has told you re his affair with the ow, if you've got a name for her I suggest you tell him that you intend to divorce him for adultery and will be naming her as co-respondent as this can be used as a bargaining chip - i.e in consideration of x y or z you won't name her.
Don't overstress about finding a shl now as there's no need to rush and a free initial consultation with any solicitor who specialises in divorce/family law - which usually lasts around half an hour - is all you'll require to get some idea of where you stand. Take a list of your queries and check them off as you go along, but don't forget to make notes of the answers!
You should also ask about the possibility of obtaining an occupation order which will prevent him returning to the marital home as and when he may wish to do so. While you may entertain some fond notion of reconcilation if his affair proves to be shortlived, you are best advised to make your home your castle in order to get the message across that you are not to be trifled with - you haven't had all of this devastating upset just for him to come crawling back only to do it again with another ow in a couple of months/years time.
Once again I re-iterate that there is NO NEED for you to rush or commit yourself to one firm of solicitors thereby beginning to rack up legal costs at this point in time as the most important item on the agenda is that you are safely delivered of your dc and are able to enjoy stress free time wtih him/her before putting your mind to the practicalities of divorce.
Needless to say, I share buds opinion of your spouse and I, too, hope you have rl support from friends/family members. I would also urge you to rest up and get as much sleep as possible before the birth.
Do come back with any further queries you may have.