Once admin has ready your introductory post you should get access to most of the board, and you'll be able to do a diary, it's just the receipe section that takes a bit longer.
You can have a weekly weigh in thread to record your progress, and we also have a slimmer of the month challenge, you're probably not too late to join for January it starts with next weeks weigh ins but you have to have been weighed (or weighed yourself) this week as your starting point.
I don't think there is a SW thread on here anymore it's all low carbing etc.
There's lots of support and encouragement, recipes, challenges and you can post a diary, there are diary monitors (like me), who'll have a look at your diary and offer some advice, or just tell you when you're doing great .
It's great for mid week support for those who go to group, but lots of members are going it alone and really appreciate knowing there are others out there doing the same.
Its often known on here as "the sparkly place", it's under new ownership and being revamped at the moment, so if you're doing slimming world why not come and have a look.