Just email the court the day before the hearing to let them know who is representing you. You don't need to email the other side at all - they can find out on the day - it's all part of various strategies. If you tell the other side in advance they will research your lawyer and plan a strategy accordingly having worked out their style, weaknesses and strengths. Which could be quite fun if you then use a different lawyer and they don't know till the hearing day
. It really is dog eat dog and strategy.
Anyway - all you need to do is send the court a brief email the day before a hearing and say - please note I will be represented at the hearing on x date, by counsel Mr X who is acting on a public access basis.
And that's all. Any lawyer you use should inform the court themselves anyway, but sometimes they ask you to do it (if it's a direct access barrister eg).
Negotiations don't happen till you're at court anyway (and you don't necessarily want them - depending on the circumstances). No need to fill in any forms. I didn't even know there were any. Just did what my barrister told me and emailed the court the day before.
Sometimes the other side will be fishing and ask if you're represented - you don't have to reply - they'll find out. What they're worried about is your barrister might be better than theirs - and you don't want them to know.
Things change at the last minute all the time and that's accepted. I applied as an LIP the first time, had an urgent hearing 2 days later and instructed a solicitor at 5pm the night before so nobody knew I was represented till I got there - because it didn't happen till the 11th hour. I had been going to represent myself but when it became clear my ex had a solicitor I panicked and got one too. They slipped up there by sending me nasty letters so I knew she was represented! If they hadn't done that I'd have gone along on my own and - might have gone ok, who knows, but I doubt it as the allegations were nasty and out of the blue.