Your kid's first musical instrument. It's counterproductive and false economy to buy them a piece of shit guitar or tuba or whatever it may be, in the belief that "if they like it and want to continue with it, I'll buy them a better one in the future". You might well turn the kid off the instrument for life if their instrument is harder to play/maintain and worse to listen to than it ought to be.

If you want your kid to be enriched by music and to be creative, buy them a decent mid-range instrument. Make it so that the kid can't wait to pick it up, don't make those crucial early days of learning the instrument feel like eating watery gruel for months with an expectation of pizza at some point down the line. A shitty instrument will be an additional barrier the kid will need to deal with every time they use it. Get out of their way, buy them something serviceable. If they lose interest regardless, well at least you know they had a fair shot at it and it wasn't the crappiness of the instrument that caused them to abandon it. And you can always sell or donate the instrument if they really don't give a shit about it.

The best instrument you can reasonably afford is significantly more likely to hook your kid than a £50 piece of junk would. It doesn't need to be fancy, it just needs to be well-made, pleasant to play, and easy to tune/maintain/clean/whatever the case may be.