Help! Can I go from a UK 10 to an 8 in 10 weeks?!

Well, I'm sure you're going to get a lot of answers here, but seeing as you are already at low weight/healthy weight for your height, I'm going to say no not a good idea to even consider trying to lose ten pounds in 10 weeks. Also, the less you have to lose, the slower and harder it will be to do so.
Any way to get the dress altered?
And congratulations on your wedding! Best wishes to you! (Please consider another route besides trying to lose 10lbs! You have more important/better things to worry about...like getting married!)

If you don't want to do alterations:

I think 5-10 would be a reasonable goal. 15 would probably be too aggressive (meaning: take a LOT of work and adherence, potentially make you miserable, maybe not be healthy). Wedding and amazing vintage dress should mean you spend the next 10 weeks all excited, not miserable, and you're going to need your energy and an even temper, which aggressive dieting can compromise.

That said, it might be less stressful to do the alteration.

Am I the only one wondering why the OP didn't just buy the dress in her current size?

misskarne, because vintage dresses come in the size of the woman they were made for originally.

Well, I found that in the smaller sizes, losing a size went much faster than in larger sizes. The difference between a uk 10 and 8 is less than between larger sizes.

A pound a week is a reasonable goal (yes, even at a lighter weight--I had no problem losing at a pound a week, all the way down to 117), but it will take close adherence to your calorie goal. Are you willing to weigh everything to ensure you're eating what you want to be eating? If you do want to lose ten pounds, you won't have much wiggle room in your intake. Are you able to easily keep to your calorie allotment and not "cheat" or splurge for ten weeks? If you have that kind of willpower, then give it a try. Evaluate how you're doing in four or five weeks, and if you haven't lost four or five pounds, then I'd suggest looking into alterations at that time.

Can you wear shapewear under the dress?

As the poster above pointed out, it's a lot safer to just alter the dress so you KNOW it'll fit, because there's always a chance that even if you try really, really hard, you just won't lose the weight you wanted to. Then you'll spend your wedding day feeling uncomfortable and, if it's tight in the way that the ill-fitting bridesmaid dress I wore last summer was, dizzy from lack of oxygen on account of your ribcage being unable to expand against the crushing pressure of the corseted satin. 0/10; would not recommend. (I ended up taking a suit jacket from one of the groomsmen and wearing it most of the night in order to cover up the fact that I had the dress unzipped as far down as my waist. I just kept telling everyone I was cold.)

Research seamstresses in your area and find one with really good reviews so you know they can be trusted with an irreplaceable dress, and have the seams loosened just a little bit. It'll be worth it.

Jamaelsh wrote: »

It's just an estimate but I think I'd have to drop 10-15 lbs to be comfortable in it. Has anyone managed this in 10 weeks? Is it even possible???
(Forgot to mention, Im 5'5/6 - currently 135 lbs, average frame?)

Yes, it's possible....but as you are at a good weight already it will be hard! Believe me i know....it was v. hard for me to lose just 5 pounds (at 5'4 and 135).
I think maybe you could go to your local Gym and ask them to put you on a lifting program. I've seen many Ladies on MFP that swear by weightlifting.
It actually changes your shape without having to lose too many pounds.
Cardio and healthier eating will obviously help too.....but maybe check out a lifting program.

Personally I'd just get it altered.

I'm not 100% but the difference between a uk 10 and a 8 is almost certainly NOT 15lbs. You could probably fit into it better if you dropped only 5-7lbs? if you can get into it now you can't be far off? I'm roughly your weight and swing between a uk 6-8 in trousers/skirts at 5'5 (I seem to carry my fat internally) with a weight variation of about 7lbs. Trust me, the smaller the size the fewer lbs it takes to change dress size/fit into snug dresses etc.

You should be fine to lose about 5lbs in ten weeks if you really don't want to get it altered.

I'd suggest all the suggestions! Try to loose about 5lbs (.5/wk) see a tailor, find some "supportive" undergarments (nothing crazy, see spanx) and, if you can, lift heavy to tone up.

Something is bound to work a bit!

Congratulations!