Hello there.
Very interested in your commute. Recently started job 20 miles one way and am determined to ride all week. So far its tough. Yes there are showers. Its a great and varied route, with hills, descents and some technical. Yes its quite a distance for no spring chicken. Yes it has its dangers (doesn't riding anywhere have this now?) Never seem to have enough food. Starting off two days a week to build from there. Have a decent bike, kit, lights and attitude. Everyone I know is saying its not possible which makes me want ot do this all the more.
Any hints or tips?
Build up gradually. The weather is improving and by summer I'm sure you will be doing 4/5 days a week.
Keep your bike properly maintained.
Look at the weather forecast and check outside your front door and then select your kit for the day.
Hydrate yourself properly at work and eat!
Bring food and water with you. In summer, I have a couple of emergency gels and 750ml of water.
Make sure you have tools and can do at least basic bike maintenance.
I'm fortunate that I can cut my ride short if the weather is horrible and get a train - do you have a bail out option?
I'd go for mudguards for long distance commuting.
I let the bike carry my gear and don't use rucksacks.
Try to travel light – obviously preferable.
If it's icy, do you have ice tyres? If not, I'd consider not riding.
Can you vary your route - I like a change now and again.
It might be worth reading Cyclecraft if you've not riden for a while.
Enjoy the ride.