sorry about the breakdown of your marriage, must be very difficult for you, particularly with a young baby.
Please be aware that no matter what good intentions friends may have in giving you 'legal' advice, you must bear in mind that every financial divorce case is different and you simply cannot compare them. It would be virtually impossible for anyone on here, or in RL to give you accurate advice on the financial aspects of your divorce without having full information regarding a number of things, ie the full matrimonial assets, ages and sex of children etc and you can't possibly provide that on here.
Ideally, you and your DC would remain in the former matrimonial home (FMH). However, we do not live in an ideal world. As QS has said, your DH will still need to be re-housed and it is very rare that there is enough money in the 'matrimonial pot' to provide the same standard of living for you both that you previously enjoyed.
If you are unable to reach an agreement between you regarding the finances (including the FMH) then the matter will have to go to Court to be decided by a Judge.
The Courts paramount concern will be the welfare of the children, and that they have a roof over their heads. If it is possible that you could stay in the FMH, ie you could get a job and contribute towards the outgoings, and your DH could be re-housed elsewhere then great. Potentially therefore you could remain in the FMH and an agreement could be reached (or ordered by the Court) that it be sold at a certain point in the future and at that time your DH would receive his share of the equity. The usual trigger events are your re-marriage, (some Courts will also say co-habitation for 6 months but some won't) your death, voluntary sale the property or the youngest child reaching 16/17/18/ceasing full time education (whichever is agreed/ordered depending on circumstances)
Depending on a number of other factors (ie your DH's pension value and other assets) it may not necessarily be a 50/50 split of the equity.
If there is simply not enough money to keep you and DC in the FMH and re-house DH then there may be no option but to sell the FMH and purchase a smaller and therefore cheaper property for you and the children which would potentially free up a lump sum for your DH to use as a deposit and/or reduce the mortgage payments and therefore the amount he would be paying each month so he could afford to buy or rent a smaller/cheaper property for himself.
What needs to be taken into account is the ages/sex of your children. For example, with 3 children now, if you are in say a 4 bed house and the kids have their own rooms, potentially if you had two boys and a girl or vice versa they could share a room and then potentially you could 'downgrade' to a 3 bedroom house. This is the way your DH's solicitor/Courts would look at it.
However, as I've said above, without someone knowing all the full information which you couldn't possibly put on here, it would be impossible to advise.
All I can recommend is you checking that your solicitor is a specialist family one and ideally, a member of 'resolution' which encourages parties to resolve matters as amicably as possibe which is so important when children are involved.
I would add, that I would have hoped that your solicitor would not have that the house MUST be sold if he/she thought that there was a chance you may be able to keep it.
Good luck