Welcome Bearsey.
You have the advice on the bike, and it's model that a lot of folks have ridden mondo miles on around here.
There's a good chance there is a fellow forum member somewhere around you're area, it's part of our global domination plan
and possible someone may know of a good shop. If you want to, let us know where you are and maybe we can be more than just moral support. If you're anywhere around me, I would be more than happy to help you in the shopping/selecting/yada yada yada. You get to name the bike all on your own though!
It's fine to be sick of the situation, just don't be down on yourself. You are making a very wise decision for all the right reasons. You get a bonus discovery down the road in that riding is a great experience, you just happen to lose weight and get healthier doing it.
Remember that early on it's going to be a challenge, with sore muscles, some mechanical frustrations, and probably a sore ***. That has nothing to do with how much you weigh. A Skinny Mini has the same issues when they first start out. If all you can ride is 1 or 2 miles, or even once around the block when you start, thats OK. It's further than you rode before and will get longer as you stick with it.
I'll throw myself in there with bautieri and say PM me any time you want to talk or just shoot the bike breeze.
Oh, and get some whitening tooth paste. You're gonna be grinning when the pedals start turning!