Would an iPhone 5c work for this?

[crochetractor]

I want to get something for dd to watch YouTube and Netflix on but I've only got a pretty limited budget of about £80.

I'd like to get an apple device because that's what both of us know how to work but the newest I could afford with my budget is a iPhone 5c or a 5th gen iPod touch.

I know neither of these are still supported by apple but I don't really know what that means and wether I'll be able to use them for what I want??

No longer supported by apple means that they won't be able to run the latest version of the operating system and will start to get 'left behind'. Over time as apps get updated they may stop working with the old system or not work correctly with it causing bugs/crashes.

My dd is currently using a 5s and an older ipod (probably 5th gen but not sure) and at the moment they both work fine to run netflix and youtube, if a bit slowly at times. I think both devices are pretty much on the way out tho - I'm anticipating having to get her a newer iphone by the summer (probably depends on how long I can cope with her frequent ranting about instagram crashing)

The amazon fire tablets are pretty good if all you want is netflix/youtube. Cheap and cheerful, and they do big discounts on them fairly regularly too (we picked one up for £25 in the summer)

Amazon fire tablet if you don't need for an actual phone. You can get a new one for under £50 even less in Black Friday deals.

I don't want her to be able to use it as an actual phone but I would prefer that size of screen as she's pretty uninterested in bigger screens.
Always ask to watch stuff on a phone rather than the tv or the iPad at her gran's.

Have a look at the Kindle Fire Kids

The Apple devices you mentioned no longer have updates so I would be concerned about how long they will actually be useable for. Some apps are already not compatible with the older versions.