Ok so I 've done a bit of an edit... Might be good if you paraphrase exactly what the solicitor's letter is wanting from you. IF you want to write it word for word you're welcome to PM me and I'll work on a full response. But from your first draft I've tweaked spelling and added a few bits of my own. Feel free to use it as is or change it as you see fit.
I have not addressed some of the new stuff you've mentioned like list of specialists or your current arrangement with your partner because I don't know the answer... How is going with current partner? all good? if so state that. But add a few sentences about how this is an un-neccesary intrusion into your life. I'd suggest you agree to make a list of all the specialists you've seen in the past 2 years but that you'll need some time to organise that with your GP but you're prepared to provide this information as a gesture of good will. However, you would like it noted that the ex has already made unreasonable demands and even when you've complied she still has not provided access and as such you're only prepared to agree to provide any further information under the condition that she now agrees to resume the previous parenting arrangements.
Dear Solicitor,
Your client MS XXX has refused myself access to ZZZ my youngest daughter since 14th October.
This letter is to convey to you that I wish to continue the care arrangement that has been in place for a number of years, without incident or risk to the children. There is no valid reason for the care arrangement not to continue.
Your client's decision to unilaterally withhold ZZZ is impacting ZZZ's right to have a meaningful relationship with me, her father.
Supervised visits are not necessary, nor are they in the best interests of the children.I do not pose a physical or psychological risk to ZZZ. I have provided a doctors certificate to confirm that I am capable of fulfilling my role as a parent when the children are in my care. I provided a copy of the Doctor’s certificate to your client upon her request. I feel this is an unnecessary invasion of my privacy however, in order to alleviate your client’s concerns, I acquiesced to her request. Despite complying with the demands made by your client, she is still refusing to facilitate access with XXXX. This point needs to be emphasized. Your client demanded a Doctor’s certificate and assured me the normal parenting arrangements would resume upon meeting her demand. I complied. Your client has not complied.
The letter from my doctor dates ???? demonstrates that my health and mental health is in good order and that i have the capacity to look after our children. I am managing my mental health with doctor check ups, psychologist appointments and medication.
I want to emphasize that I am providing information to your client that she has no right to demand. However, I am providing this information in the hope that your client will agree to resume the normal parenting arrangements immediately. I have a medical professional who has confirmed that my capacity to parent is not in question. With that in mind if your client insists on refusing to co-operate I would like a written explanation.