If you have the NOW Freeview Smart box with the blue NOW TV logo on the top casing then unfortunately Disney Plus removed support on this box after the 31st of May 2023.
The older NOW black box, NOW 4K Smart box and NOW Stick still supports the Disney Plus App on them.
One thing to be aware of is that the original chrome cast is on its last legs, and will soon no longer be supported - as google are due to stop updates soon - it may also not work with now. so avoid any offers or dirt cheap prices.
Like wise with other android TV sticks .
My general recommendation is t to choose either a Roku or Amazon fire, and spend a little more for a better model
However if you are looking for as cheap as possible then
probably the cheapest, but will also probably be a little sluggish and slow to load a few things - however the speed aspect will only be noticeable if you use other streaming devices, also no 4K support (1080 max resolution) and a basic IR remote
Argos also have the Express for £30 ( not much of a step up over the SE) with the 4K version also at £30, the stream bar on offer for £60 and the 4K stick for £50 Streambar and stick also feature TV volume controls on the same remote
Fire sticks start around £35 , £45 and above gets you one with TV volume controls on the same remote with the 4k version at £65, and the 4Kmax at £65
I own both Roku and fire stick, my personal preference is for the roku as the layout is cleaner - a basic list of tiles representing the various apps ( such as iplayer/now/disney plus) which you can re-order as you please and not much else, where as the fire sticks/devices put amazon content front and centre and are designed for you to buy content from amazon complete with a preview/video paying in the main menu screen and the various apps getting far less prominence
£ for £, Roku devices are significantly cheaper than Firesticks.
And nicer, in my personal opinion, with a much cleaner interface, where I agree with @chilli2
Roku Expresses aren’t sticks, but even on a TV on the wall, you can affix it under the bottom bezel of the TV with the double-sided sticky tape they give you. Looks very neat, practically becomes part of the TV.