Hi all
@Whorty I have the 'conti four seasons' on my commuter and they're very decent. Somewhere between the 'gp4k's' which are quicker but not as durable, and the gatorskins which are more durable but not as sprightly. As others have said get 25's rather than 23's.
With regards the saddle I'd get on the case asap mate. Give yourself a chance to test ride more than one over a decent distance out on the road. As AAAC said cushioning level can be overrated. It's definitely a see what fits your butt best thing. More expensive doesn't mean better, probably just lighter.
I'd say don't scrimp with the bib shorts though. You can pay more depending on the label attached but it's vital you're happy with the padding and fit. If either of these things are a bad fit it can cause big problems. Not trying to scare you but I'd definitely buy a few pairs in different sizes and styles, pick a favourite, and send back the ones that don't work for you. Just buying one pair is a bit of a punt in my opinion.
Gloves are going to be important too. I don't know what
Halfords range is like but I'd try a few pairs. Personally I've gone back and fourth a bit but I think on balance I prefer the ones with gel in the palms as opposed to different variations of padding.
I'd leave the rack at home too mate. How much do you really want to carry? As kipster says there's a danger you load up with things on principle but don't really need. A saddle bag and a cycling jersey with back pockets should do nicely.