I have an ileoanal pouch, have had for 10 years, and I'm pregnant without any intervention. It did take 10 months, but I have arthritis as well and think that was the bigger problem - so if you have the chance to get rid of your autoimmune problems then it is worth it. In the future, the fertility service will fast-track you to check that your tubes are clear as the scarred tissue is the biggest fertility risk. Having the surgery before it becomes an emergency is also the best course to maintain fertility.
As far as I remember, the colectomy part of the surgery and formation of a stoma is not linked to any decrease in fertility but the formation of a pouch (2nd op) increases your risk of infertility from approx 10% to approx 20%. However, both these options are better than with active UC. Therefore, if you are already thinking of TTC you could consider having the stoma while you have your children and having the pouch formed later. This is a personal issue, as a stoma can be difficult, but it is an option your surgeon and nurse should be able to discuss with you.
It doesn't sound like you have been very well informed, the first operation has a three month recovery and 6 month gap before they will form your pouch at the second operation - so you will have TTC on hold for about a year. Most surgeons insist on a third operation after that before pouch is attached. If you just have the colectomy, it will be 3 months but you will then have a stoma. You will be UC free then though, which shouldn't be underestimated. There is a support group but it is very biased towards bad stories, so I would approach the support nurse first, the people who have had nothing but success tend not to join support groups as they are too busy and it doesn't occur to them.
FWIW, these operations were the absolute best thing that I have ever had done - you won't realise how much the UC is ruining your life until you get rid of it. Good luck!