Good station, bad assistance!
This review is especially helpful for those who have or use the following: Assistance Dog - Visual, Long Cane, Symbol Cane
I've travelled to Euston Station regularly. The overall accessibility is good - with lifts, escalators, level entry, and accessible toilets - all on site. Where it lets itself down is with its assistance staff - they either don't turn up, turn up too early, or take you to the wrong train. That's what lets the station down.
Transport & Parking
There's a bus station outside Euston station and a London Underground station too. I'm able to use stairs, so I don't know how accessible the platforms are for wheelchair users.
Signage is large and clear, there is level access throughout. Whenever there are stairs, there are lifts or ramps nearby. The only downside would be that, when trains are announced, everyone rushes to their platform - which can be problematic for VI passengers.
There are two accessible toilets I know of - one near platform 1, and one up near the first class lounge. Both are spacious enough, and both have red cords. There could always be more space, hence the 4-star review. I don't know if there's a changing places toilet on site.
The assistance staff let the train station down. I've regularly been forgotten about, and even once taken to the wrong train. Often they're confrontational if assistance isn't booked in advance.