Wedding outfit HELP!

[MothInMyKecks]

Please can someone help me?
I need to attend a wedding a week saturday and I've been putting off buying an outfit because I feel so huge. I'm a size 14 (and before you all say that I could be biggerl), I have a very very wide set of shoulders, a broad back, huge upper arms (think of popeye - no kidding) that are very un-toned, and I've become really flabby since the Spring. I really am quite shapeless.

I feel really unhappy about the way I look in general, so am dreading having to go out shopping. Does anyone stylish out there have a clue about what I can wear? It must cover up my arms. In fact, perhaps I should just get a huge sheet and cover everything up.

Meant to add that I prefer internet shopping to avoid changing rooms.

I think Internet shopping is great but it s a pain when you dint get to try stuff on or if it doesn't fit. And you often still need shoes bag etc! Block off a day, the night before defuzz your legs / underarms and if feeling up to it put on some fake tan, that way you ll like your reflection a bit more. Wear comfy but not awful clothes shopping - nothing like catching sight of yer bum in trackie bottoms in the mirror of a nice shop to kick your confidence to the cobbles. Don't wear too much jewellery or fiddle y bits n bobs - having to take off and put on lots of Layers scarves tops etc will wreck your head and seriously curn your enthusiasm.
Then go try on a few styles, I bet you look much better than you feel and going out trying a few bits on will help.
If you re not very keel on your shoulders what about something patterned that would draw attention to your bottom half or waist ? I don't know how to link but there s some nice colour block dresses about at the moment too might be worth experimenting with

What's your budget?

How about something like this or this?

Budget is about £100 max for dress. I like the first one.
Quite like the idea of a wide brimmed hat too, but that's another pot of cash.
Thanks to you both for replying. Every but help