45 miles, but there is a sauna...

I eat way too close to my departure time... I get "acid guts".
I then can't face eating anything for a while - which is a big nutrition fail.
Replace fuel on arrival to work to keep metabolism high - and in an anabolic state.

Can i just add too? Make sure you enjoy your ride in! I know this sounds daft, but a mate of mine ditched his bike recently cos he totally messed up his organisation. He hated every minute of the commute, and was always poorly fuelled... now he hates two wheels.
So vary your route, mix it up. Take the train on occasion so that you end up "wanting" your bike (not in that way, but whatever floats your boat) and you should be onto a winner.
Good luck!

While I understand the sauna on arrival, the sauna before going home could cause dehydration and is probably best avoided.

Going in a sauna never causes dehydration if you do it correctly. Always drink while you're in the sauna, drink cold water with ice and you can stay in longer. By longer I mean when you're starting out some people can't handle staying in very long.

If you can, eat before you go in the sauna, like an apple and a handful of nuts. Drink iced water the whole time you're in there. If there's a cold plunge, alternate between the both of them.

When you're doing that many miles you really need to contrast bathe at first until you get used to it. End on heat when you're about to go riding, on cold when you're done with your riding.

cold when you're done with your riding.

Yep. I got to the office still sweating this morning.

Well, the contrast bathe is good b/c it's like a whole body pump of your blood. Hot water dilates vessels, cold contracts them. This isn't just blood vessels but also lymph vessels.

If it's a good bag and has enough adjustable straps then it shouldn't be a problem, I can cycle indefinitely wearing my PAC, I feel weird when I ride without it in fact.

Exactly, I mean if you get yourself a decent bag like a pac ultimate, or an Archies Archie etc then you should barely even notice its there. I've done several 30-50 mile rides with my bag on with no probs at all, a couple of them I was even loaded up with quite a bit of stuff: Laptop, Charger, tools, change of clothes, 2l water, miscellaneous camera equipment lurking in there as well such as flash brackets etc.
As Will says, nothing that your average courier wouldn't do in a day, and with a good comfy bag that fits properly, you'll be golden :)
Clothes wise though Hippys suggestion is really good, for just over a year now i've stashed all my work clothes at work, and if it means you get in on time/early most employers are pretty accomodating.

Well, the contrast bathe is good b/c it's like a whole body pump of your blood. Hot water dilates vessels, cold contracts them. This isn't just blood vessels but also lymph vessels.

Great advice :)

Done. Knackered. Blimey, I have to do this every day?! It's almost time to get up again.

Aww :(

Well done man, Sparky ... eat well, sleep well ... and settle into a rhythm ... also keep in mind that you don't HAVE to do it every day, right? I'd factor in rest days over the first two weeks for sure. In the end it will become less of an obstacle I am sure.

Edit: A rest day a week will still work out cheaper than taking just the train after you've folded for good. So it's in your best interest not to wear yourself out.

i used to do a commute from falmouth to st ives (22.8 hilly miles) 4 or 5 times a week. funnily enough i also did it on a fuji track with freewheel. now i have a roadbike i reckon i could do it alot easier/faster.

the biggest problem i had was dealing with country roads in the dark, big lights were neccessary. i also used to get quite alot of punctures from the stone chips that litter the country roads. i find early mornings tough, especially if ive been smoking the previous evening, but getting up to do some excercise seems to re-inforce the routine.

i didnt do anything special for the ride and just went in my normal clothes, but changed into a fresh shirt when i arrived. i ate alot, but when im not commuting im doing rides of a simlar length or longer so its nothing out of the ordinary for me.

its a fairly long commute but itl be fine if your already a good rider, and you give yourself enough time as to not have to rush yourself. my commutes to/from work are normally the best part of my working days.

Done. Knackered. Blimey, I have to do this every day?! It's almost time to get up again.

in a month time you'll come back to read this and think "fucking hell, I sound like a baby".

Iced water can overstimulate the Vagus nerve, causing a sudden drop in blood pressure and heart rate, which can lead to passing out. You don't want to be passing out in a sauna.

It's the same thing that happens when you jump in a plunge pool and your breath catches.

Speaking from two years of sauna/cold plunging weekly, I needed ice water or I overheated too fast. You just sit while you're in there and don't cover your head like the crazy eastern europeans! Or if you want to lay down then get up slowly.

I ended up doing around 10 mins in the sauna, 2-3 mins cold plunge (until my core cooled down) and then back to the sauna, three times and then out drinking! It was a weekly after-work relaxation thing with fellow massage therapists. We called it Detoxing and Retoxing.