It's tricky to plan because the financials will depend on the childcare arrangements so what I would do is a "best case" and "worst case" scenario (which depends not on some linear measure of "good" and "bad" but what works for you and what doesn't) and then form a plan for both.
For example, what your earning capacity is depends on how much you have the children. If you have them every school night, then given the children's ages you are only going to be expected to work for 25 hours a week (full time I've heard anytime from the time the youngest is 11 to 13, I don't know which and you would need to check with someone more knowledgeable of that area!) On the other hand, if it's closer to 50/50 then that might mean 2-3 days a week that you can work. Or you might decide between you to have wraparound care and both work full time.
So, in a nutshell, you need to first consider how much or how little you will be able to earn yourself in the range of circumstances. Also, bear in mind your earning capacity doesn't just mean carrying on in a minimum wage or other low hourly rate job if you have skills and qualifications. For example, if you are a graduate it'll be assumed you'll gradually progress to something better paid and if you have a profession you will be expected to return to it.
Once you know your maximum and minimum, next work out what the child maintenance from your ex would be in each scenario. You can use the government calculator for that. 50/50 care would be zero but better prospects to work longer hours, something closer to EOW means he will have to pay you based on his income.
Third, you need to work out what universal credit you might receive. I used to tell people to use EntitledTo but I find this one better: www.universalcredit.co.uk/calculator/
If you are the resident parent you can also receive child benefit and also remember whilst you are the only adult in your household you will be entitled to a 25% reduction in your council tax.
Put those figures together and that will be your highest and lowest likely income. I didn't mention spousal maintenance because I don't know what your DH earns. If it's over £100k you might get something for a couple of years although it will reduce your universal credit claim so it might be better to get it as a bigger asset share. If he's on £200k plus or if you were approaching mid-fifties it might be for longer but I'm assuming that doesn't apply to you with a 7 year old.
In terms of assets, again, it depends where the children are. Speak to a solicitor as well, because what follows is just snippets of what I've learned without a full awareness of the whole. If it's 50/50 care, then the asset split might be similar except for a tweak to allow for your lower earning capacity. Again, that all depends on what your DH earns too and this is very unpredictable. I've been told every single case is different and it's more important to focus on yours and not listen to what other people got. It tends to be people egged on by friends who "did well" who end up giving half their equity to a lawyer (if you do use a solicitor - and in my view I think you should because mediators aren't always that sharp on the law - make sure they are a member of Resolution).
However, strictly as a general rule if the children spend most time with you then something in the realms of 60/40 to 70/30 are likely depending on how much DH earns. Main assets are normally the house and a pension (which you have to get valued, because it's value today is worth less than the face value because you have to pay a lot of tax to withdraw it, you can't access it until 55, investments may go down as well as up etc).
If it's closer to 50/50, DH's needs will mean an asset split closer to that although his higher mortgage capacity in the short term might mean you get more of the house and he gets more of the pension.