If your solicitor isn't available then you need another one. You must have someone who is very good at family law.
You having given up your career for his will be accounted for. There are various other entitlements. There is also your option to require half of all assets and half of his pension, etc.
Don't mess around with this. Don't go into mediation with no plan. You may feel pressured (by yourself) to seem 'reasonable' and agree to something. You MUST act under the advice of a solicitor.
Regarding children, it does sound as if there are reasonable concerns from his conduct up to now that he isn't good as giving them educational support. However, as someone has said, that doesn't mean he can't start to try. In any application to the court, his known behaviour would have to be clearly listed as part of your reasoning for wanting the children more. Again, though, this might not be considered sufficient reason to set 70:30. It will be up to what the court considers in the best interests of the children. It may find that indeed you have more time for them particularly re school, and that you have been the sole provider of this support. As someone mentioned, a common split is:
Every other weekend
One school pick up (but maybe not overnight as disruptive for school morning - back to you by 7pm)
Half the holidays (arranged so they don't have to go a long chunk without seeing either of you)
Ideally they wouldn't go longer than about 4/5 days without seeing him in term time.
The same court does finances and arrangements for children. Both issues can be dealt with in the same hearing.
I would answer the mediation request that you are very happy to come to mediation, but as all the relevant information isn't yet available, suggest the meeting is held when it is, as nothing can be agreed until you have that.
You need a solicitor also for checking spousal maintenance. If he's been the earner and you've looked after kids and home, aside from child maintenance you may be able to apply for maintenance for yourself, so you can continue to live in the manner you have during the marriage.
He has had advice and you haven't. You can't go into this unprotected. Get a good solicitor.
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