Thanks again all. Went out for just a couple of miles today, and the new saddle is just fine.
The commute begins tomorrow, and I'll either cycle daily, or take the odd day off to recover if necessary. I'm hoping the former.
Diet-wise, believe it or not, our base diet is good. We (mostly my wife TBH) cooks from fresh stuff. We avoid too much fat, and rarely have sweet things like dessert. My problems are really mostly from an inactive lifestyle - desk, car, sofa - hence the changes I'm making.
I promise to report on progress - mostly as a means to 'keep me honest'!