Hi Kat, i've read through the whole of this thread and you seem to have all the exact same worries as i did before i started. I'm now in my 7th week and have so far lost 2st 1.5lbs and it's the best thing i've ever done.
I do mine through my doctors surgery and the nurse i first saw was horrible to me and said pretty much the exact same things as your chap at the chemist (it doesn't work, you won't keep the weight off, your starting during the summer hols and you've got kids so you won't stick to it etc etc).
She's now like my new BFF because i've completely proved her wrong! Just like you will with your chemist chap. I can't lie it's a bloody hard diet and at times you do feel like giving up but at each weigh in it makes it worth it as does the drop in clothes sizes. I've not lost any hair (so far) but i have had the odd mood swing. But it's not forever.
As for prices these seem to vary, I panicked about being able to pay for mine, but i sat down and worked it out - i was spending about £20 a week on wine alone (sometimes more - but mostly i was drinking because i was depressed or down about my weight etc and it just spiralled) then if you add the wispas, packs of crisps, chinese etc it soon totted up to over my weekly lipotrim spend anyway so it may be worth doing something similar to that just to prove the point to your partner about the costs.
I really do wish you all the luck in the world with this and that you get to your goal, i was 17st when i started i want to get to about 10stone but i'm just taking it each week at a time and will see how i feel when i get to a size i'm happy with when i look in the mirror so if that's more than 10 stone so be it, it's better than being 17!.
I'm 28 with 3 kids (plus a dog whos like my 4th child! lol) and it came to the point where nothing else was working so i took the leap. I'm lucky that i have my husbands and familys support and that's really important to me.
I'd maybe sit down or write a text to your partner or family and explain to them what your doing, why your doing it, possible side effects (mood swings etc). But just how important it is to you to have their support and for them not to be pointing out the costs or negatives etc all the time.
I did this and my dad (who told me on my first day that "you won't stick to it - you'd always gunna be a chunky cornish maid") actually said how good i'm starting to look and that he's proud of my determination and effort as he couldn't do it. Which really made me feel good and he never says anything like that. ever.
It's also great being a member of this site, i don't have many friends and i feel like i've always got a friend on here when i'm in need, someones always here for you.
Good Luck and keep in contact, and if ever you need some support or geeing on just do a post on here and you'll feel better in no time.
Cath.