A few letters from Family and friends saying that they believe you are very much in love and intend to spend the rest of your lives together, they are looking forward to the wedding and welcoming her to the family cannot do any harm.
The financial summary thing just makes it easier if there is any doubt - to be honest you sound prety sorted anyway. I used one becuase while I earn a lot, I also spend a lot, particulary as we bought a house 6 months ago and have spent every spare penny on refurbishment in that time. So i put in a summary showing that commtiments meant a disposable income sufficient to be comfortable. It takes about 10 minutes to knock together and gives them an immediate overview. It's about making the ECO's job easier. It is essential no, might it help yes.
Other side of the Country sounds like a Perth Girl.. I married one of those too