Rob there are two separate issues here; money and contact.
I usually say avoid sols but you do need some legal advice regarding financial affairs, selling the house and splitting the proceeds etc. Try the CAB first, though you might need to pay out for a sol to ensure you don't get taken for a ride.
Regarding child maintenance do not do this through court. Maintenance issues are menat to be sorted via the CSA and not in court any more. Tell your ex to look at the CSA website. They have an online calculator there which will give her a rough idea what she could expect to get if she went through them. You have made an offer, she is not happy. To be honest I think it is too high. The CSA calculation is meant to keep your child in the lifestyle they could have expected had you remained together. Your ex will have to lower her expectations and her lifestyle to match her financial circumstances. If she can show you that her income does not meet the needs of your child then perhaps you can negotiate a different arrangement. But you should not be paying for holidays that she wants and a house that is too big. So while I think your offer is very generous I think you should look at your motivation behind it. I get the impression you are happy to leave your ex to do the 'hard' work and you pick the fun times and are paying her off to do so.
Bringing up a child is hard work. You say there are lots of single parents who work full time. Well frankly I don't know very many and I know a lot of single parents. At the lone parent group I am a member of there are about 50 adults and only 6 of us work at all and of those only 1 works full time. Of the sinle parents I know outside this group I have only found 2 who have worked full time with young children. One of those has a teenager who does the breakfast, school drop and collection and gives his younger brother his tea. The other had grandparents who fill in the before and afterschool times.
Regarding contact - I think you are plain out of order to say your ex should work full time, have to deal with all the weekly child care arrangements and that you are happy with every other weekend and half the holidays! Is that taking responsibility for your child?! Hence why I say it seems that you would rather palm off the responibility and 'pay' for doing that by being overgenerous with the maintenance.
Your job will allow a certain amount of flexibility and I'm sure you can arrange to leave school a little earlier on at least one day a week to collect your child. You can then do marking or lesson planning on the weekend you don't have your child instead.
And don't tell me you can't have flexible hours in your job but then go on to say you expect your ex to get a full time job and be able to meet the pre and after school child care arrangements and run a household on her own.
Regarding contact I think sols should be avoided at all costs. Mediation is much better. Try and keep things amicable if you can. Your child will benefit from two parents who can work together, even if they can't live together.
If you want help putting together a parenting plan then go look at the Families need fathers website or SPIG. In fact I suggest you join Fnf. I am a member myself. It is NOTHING to do with F4J and is a well respected charity. You will get good advice there but you will also get told when you are being out of order and expecting too much or avoiding your responsibilities.
As a teacher I'm sure you can help out with child care far more than half the holidays too. Don't be mislead into thinking every other weekend and half the holidays is ok because that's the 'normal' arrangement. Your child is an individual and you should bee looking at his needs, not what you think is normal or what you want.
So yes I do think your ex is asking too much financially. But I think you are avoiding your responsibilities too and justifying it to yourself by saying 'she'd miss him if I saw him more so it's ok'
Gilly