How can you arrange flexible contact

I am asking this question from a different angle from the other Dads I see on the forum.

First some background.

I work abroad quite often. Two or three times a month for three to five days each. Over the year it will average out at 10 days a month. These times are completely out of my control as they are client led.

The current arrangement is that I have my son every other weekend plus Mondays and Thursdays so half the week.
If I miss a day or weekend, my ex-wife insists I have to make it up and take one of the other days or weekends.

So basically 50/50

This means that during the busy months (around half of them) I am either working away or looking after my son. Don''t get me wrong I love looking after him and will often take him to his sports events when it is not my days as well.

My job when not away is at an office an hour and a halfs drive each way so I also have long days as well.

I don''t want to move nearer work as I want to be near my son.

As usual with kids these days they have lots of activities and after school clubs which means you have to arrange some way of getting them there and back.

If it is my day, or rearranged day then I have to arrange getting him there and back (to her satisfaction) sometimes this can be up to 30 miles away if he is playing an away game. As I am not home in time can you imagine trying to get someone to pick up your child from 30 miles away? It is OK if it is one of the normal days, I have arranged that, but if it is an exchange day I am at a complete loss as I work so far away.

I have a new lady in my life that unfortunately lives 60 miles away and I get to see her less than once a week because I just don''t have any free days or free time.
Fortunately she is very understanding.

My ex wife works within one mile of home three days a week and also has to go to meetings say 100 miles away once or twice a month.

My ex and I have endless arguments over what is expected of me including threats of taking me to court over not fulfilling my responsibilities. (I averaged 47% last year)

One other thing. My son was born in 2001 and we were not married at the time which I know impacts on parental responsibility.

So after all that preamble my question is

What actually are my responsibilities.
She is the primary carer and primary residence so what are her responsibilities?

one last thing I am not trying to get out of seeing my son. He is the most important thing in my life. We have a great relationship and I think he is just amazing.

If you have 50/50 contact arrangement does that mean your not paying child maintenance?

If your ex took you to court, a judge wouldnt impose contact on you. In all probability a court order would result in less contact for you.

You may not have PR, but you certainly have a moral responsibility to your son as great as his mother''s. If you share care 47/53 that is about as close to shared parenting as you are likely to get and you are both effectively the primary carer (which is an expression I abhor).
PR is only an issue if your ex is trying to exclude you, but it sounds as if she wants you to be fully involved, which is excellent news for you and for your son.
If work commitments get in the way of taking full responsibility as a parent the obvious solution is to change your job, which is what many of us have to do on separation.

Yes I pay 15% of my wages for child maintenance.

I have been doing this job for 27 years except for when my son was born and I took a local job for the first 6 years and was miserable. I don''t think my son needs a miserable dad.

I don''t want less or more contact. I just need the flexibility to do my job. My ex-wife imposes so many restrictions on me and I want to be able to negotiate knowing what responsibilities we actually have in law.

I know my moral responsibilities both on a financial, time and emotional level and my son is in no way lacking support from me.

I don''t want to go to court and have strict rules imposed on me about having to have every other week otherwise I would lose my job.