I would suggest that your uncle and mother give any money directly to your children rather than yourself. This will mean that any money they give in the short term or an inheritance does not become a matrimonial asset as it never belongs to you, but rather to your children.
Something to consider in the short term is either a Junior ISA or bare trust. You would open a separate Junior ISA in the name of each of your children and anyone (including your uncle and mother) can put in up to £9,000 a year into each Junior ISA.
The good/bad thing about a Junior ISA is that the money cannot be taken out until the child turns 18 and is an adult (there is an exception if they are terminally ill or die before 18).
The bad part is that any money in there you cannot touch at all until they turn 18 (eg if you have an emergency), but that is also a good thing in that your husband cannot get at it either and it is not a matrimonial asset but belongs to each child.
Another way of doing it is by using a bare trust but this is quite expensive to set up (especially as you will ideally want one for each child) and only really worth it if each child is going to be getting more than £9,000 per year.
In the longer term it would also be worthwhile having your uncle and mother change their wills so that instead of naming you as a beneficiary they replace your name with your children (a solicitor would probably suggest replacing your name with something like "the children of stardustbiscuits who survive me" rather than their actual names in case you have any further children - I don't know if that's likely).
Since your children would be the beneficiaries of the will rather than you, the inheritance never becomes a matrimonial asset but becomes the property of the children.
Children under the age of 18 cannot receive any inheritance until they are 18. So, the inheritance will be put in trust and a trustee (presumably you) will be named in the will to look after the inheritance until each child turns 18.
As the trustee, it will be down to you to decide what happens with the inheritance until your children turn 18. If you wanted to use it to, as you say in the OP, invest in property so that there is some income for the children then you, as the trustee, can do that.
Since the inheritance goes directly to your children and not to you it never becomes a matrimonial asset.
Changing a will is something that should only be done by a solicitor or other qualified professional.
Opening a Junior ISA though is very straightforward and there is a very good guide to which are the best ISAs here on money saving expert:-
https://www.moneysavingexpert.com/savings/junior-isa/