Congratulations on your upcoming wedding!

I don't have any tips in particular - but didn't want to leave this unanswered. I would think 15kg would be doable OK in six months and maybe even 30 if you are young
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- The key to not enduring keto flu would be to stay in ketosis - but I guess you know that! Stock up your freezer with lots of lovely artificially sweetened fat bombs or keto ice cream for when your sweet tooth strikes. Or alternatively stay as far away as possible from all sweet things until your palate is re-educated away from sweet stuff. And speaking personally, stay away from alcohol as I find that's when my judgment goes awry!
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- Good luck, let us know how you get on.

Congrats, first and foremost.

Shortening the keto flu for me included fat blasting myself, ignoring calories, and majorly upping my salt to keep my electrolytes.

Keto's benefits are HUGELY negated if you're "in and out of ketosis." Find something and stick to it. Period. Going back and forth on any program will not give you the consistent successes your require to reach your wedding goal. (not being hateful, I promise ... just a little tough love/reality dose)

I was a sweets junkie of the absolute worst measure. I could sit and eat an entire large jar of Nutella in one sitting with a spoon. I could eat 3 king sized candy bars as a snack and want more. The key, for me personally, to defeat this was to drop my carbs low enough (getting below 35 at first, then below 25 for keto) to get over the carb cravings. Upping my fats. Ridiculously so, to outsiders or anyone stuck in the old "fat is bad" mindset.

When I have a sweets craving, I have fat first. Then I allow myself a keto friendly sweet. My favorite fat bomb has cocoa powder and cinnamon. (I use Pure Via Stevia. It's organic and non GMO. Liquid stevia gives me massive headaches. I can use liquid or powdered spelnda, but I like the Pure Via better.... Just FYI, everyone is different. And also FYI, before switching to low carb, I could never stand/tolerate artificial sweeteners of any kind.... Now it's much easier.) Keeping myself full up on fats and salt has killed most of this knee-jerk cravings I ALWAYS had before.

Also, I've recently switched to doing a variation of "bullet proof tea." I can't stand coffee. I use my stevia, and on occasion a sugar-free creamer in it. Mostly heavy whipping cream and coconut oil (I've used butter, but it doesn't blend as well or travel as well in my water bottle method)... I drink it at 7-8 am, and I drink broth around 10:00 - 10:30, and I'm barely hungry by noon - though it depends on the day.

Good luck looking around and figuring out what works for you. I went LCHF back on 1/15, and I've been Keto for about 4 weeks now. I've lost around 20 pounds and gone down a full pants size and am well on my way to my next one. I'm also looking at having to adjust my bras finally this week (one of my more stubborn areas). I'm losing more inches than pounds, but I consider that a win, because that means I'm burning more fats and likely building some much needed muscle...

Just my personal opinions...no hurt feelings if you toss them out the window.

Welcome Beccy, i'll second and third what everyone already stated. Remember, the willpower and patience is the key. Nothing is going to happen overnight, so give it time, and you will be successful in your journey.
The less sweets you eat the less you will crave them. Bacon is my sweet
Congrats on your wedding as well and best of luck!