So, XP has persuaded DS to stay at his and go nc with all of our family.

[Gawarngawarngawarngawarn]

This has been going on for over a month now, which there are previous threads about. DH and I have 2 DSs, who are 7 & 5, and are on the autism spectrum. I had DD and DS (17 and 13) with XP - we split in 2005.
2005 - 2010 - 50/50 split, with the kids changing house every day (at his request) but we did all the school runs, paid for all childcare and afterschool clubs, and ran around when equipment was lost/forgotten/not washed at the other house.
2010 - After 5 years of not assuming responsibility for his days of care, I changed the routine to dinner twice a week and every other weekend term time, and as much of the holiday as he wanted. At his request, we went to mediation, and the routine was changed back to 50/50 (with less frequent changes) with the understanding he sorted out travel and childcare for his days of contact.
2014 - He withheld the children, saying that they wanted to live with him. We went to a solicitor who told him to return or we'd be applying for an emergency contact order. He then persuaded the kids that they wanted to move to have their primary residence with him, so they came here for dinner twice a week, every other weekend and half the holidays.
26th Feb - DS informs me that over Xmas, XP had a couple of mental health episodes. Without going into masses of detail, it was serious enough to be concerned for their future safety. We emailed XP to say we were aware, that the routine need not change, but that we wanted assurance of their safety.
He emailed back, saying it was only one episode, and it was nothing to be concerned about - the hospital admission and the time off work was not anything to be concerned about and the children were perfectly safe.
We replied to say ok, but can you just get some verification from a professional that the children are safe.
The next day, he withheld DS and persuaded DD to stay at his, which continued until a week ago, when DD decided to reinstate the most recent arrangement with us. We still haven't seen DS. XP is saying that I'm emotionally abusive.
I've been to a mediator who tried to contact XP - and he hasn't replied her texts, calls or email, so she's filling in the MIAM form so I can send it in with a C100.

Thing is, is that we are completely skint, and while I'm trying as hard as I can to drum up clients, get another part-time job, we are not in a position to get another loan or credit card, as the last time this happened we ended up with a bill of £1000 which I'm still paying off. I had one small store card that I forgot about last year while working full-time and although I'm paying it back it's fucked my perfect credit score I've just asked my mum if she'll lend me the money, which she won't - fair enough, it's her money to do with as she chooses, and she wants to make sure she has that in case she or my Dad die or they need a boiler. That's her choice.

SO, what I would like to know from other mners, is if anyone's had a similar case, gone in and represented themselves, and what happened? As far as I understand it, the start of the costs will be for the two forms, but then what? I can't seem to find out much information on how much things will cost after that.

The alternative is of course, not going to court, but then DS will forever think I didn't love him enough to try and get him back, and although we're not likely to have a court go against DSs wishes, at 13, feel that we must at least try and get some kind of contact back with him, even if he hates us.

Nothing.
Once your application is issued, CAFCASS will do safeguarding checks (which in light of what you have written might raise concerns about XP) and the matter will be listed in a conciliation list, i.e. a hearing where you get to speak to a CAFCASS officer either with XP or apart and that officer makes recommendations to the judge as to the future conduct of the case. Almost certainly in the circumstances you describe, the court will want to hear from the child which is done by means of a report from CAFCASS who will interview him, speak to his school, to you, to his father and anyone else relevant to try to get to the unvarnished truth about the child's wishes and feelings.
The court will then be all-but-obliged to follow the recommendations in that report unless there are good reasons why not.
All of this is entirely achievable without legal assistance.

Ok thanks - I just have to hope that CAFCASS will see through all the rubbish XP has been spouting about me then, which is a bit more risky than I thought. I knew that CAFCASS would do safeguarding checks, but thought that it would automatically go to a first hearing. Thanks for the heads up. Do you have any idea of how long it might all take, in a best case scenario?

And I'm interested to know what it is about my post that raised a bit of a flag about the XP and safeguarding risk? Is it the fact that he's withheld him, or the fact that he and my son are alleging emotional abuse? Obviously DH and I think it's bullshit - DD has come back and is trying to act as completely normally as she can, and we think that if he'd had grounds for this before now, he surely would have, and should have, acted on it in another way?

Sorry - just realised which post this was replying to, and that I'd mentioned the MH episode in this post, which would be the flag you were talking about. Sorry!

The rule in the Family Court is Safety First. Accordingly even things that might turn out to be nothing will be flagged at an early stage.
Now mental health covers a huge range of issues from the mundane to the seriously dangerous, but you mentioned an episode of sufficient seriousness that it led to a hospital admission. On the face of it, that might pose a risk to the emotional wellbeing of the child, particularly if he is on the autistic spectrum so requiring more than ordinary stability.
You should get a mediation list appointment within about six weeks.

sorry, conciliation list

Oh, ok. That's really really helpful to know - thank you so much. We have suspicions that there has been a lot of 'stuff' going on, but are being really careful to make sure we are logical, calm, and reasonable. As far as I know, Social Services aren't involved with the children over there, (DS1 isn't on the spectrum, but the younger two DSs are) but DD and DS1s behaviour has been erratic enough (outside of what you would expect for their ages) to make us think that something weird is going on, but of course, we can't (and haven't) pressed them on what, and we haven't included any of this in the form, mainly for fear of that being seen as eagerly pointing the abuse finger back at him. Thank you so much for the advice though.