Virgin (the only run the west coast now) always have two reserved bike seats in carriage A next to the bike storage. Only found out as a guard told us. The stressful bit us worrying you will not be able to get the bike off if your stop is not the terminus.
Meanwhile in Italy every orher carriage takes bikes.
Yes, I'm usually getting off at the terminus. It's important to find the train manager on getting on to tell them that you will need letting off. Their base is some sort of mini cubicle somewhere near the middle of the train but they do go wandering a bit. Thanks to the seating near the bike you can pop into the storage to check that your bike remains on the outside of the bunch if you need to get off pronto.
I am afraid Italy is actually worse than the UK with regard to bikes on trains - I fear you might be falling into the trap of slagging of us Brits in comparison to our supposedly more enlightened euro partners - very common these days. In Italy, last time I checked, you actually have to buy your bike a separate ticket. Yes, buy. Even though in the bit of Italy I used trains and bikes the trains were often virtually empty - cos Italians are car addicted and would rather drive - even, notoriously, virtually to cross the street. Not wanting to treat my bike to a separate ticket, or buy it a romantic meal for a dirty weekend, I used two types of folders - a Brompton and a Dahon folder. But I once had to pay for the Dahon.
Again last time I checked Italian rail used to have a special day, repeat single day, per year, when you could take your bike with you for free. O thank you oh mighty baron, Trenitalia, we are not worthy.