You won't get a Kit that is any good and if you do find one it will probably be equal to your total budget just for the frame. Like that flimsy rubbish you showed is £450 just for the frame without any motors etc.

I've given this advise many times to those on Low budgets with around £1000 and it's Wait and save up.!! . . . 1K just isn't enough to get a fully working decent machine but it's over half way. Like Neil suggests 1.5k is realistic minimum and even then you'll have to DIY every thing your self and shop careful.

If you try to build with 1k you'll end up wasting money as you'll probably end up buying cheap nasty components that are not suitable. End result will be an under performing and likely unreliable machine. Honestly your better not bothering and saving up.

Or build the machine in phases and save as you go along but still buying the correct parts. I've helped many people who are skill or equipment limited has well has budget limited build machines this way and while it takes longer you end up with a great machine custom built and worth having that is often worth twice it's component cost. Rush and you will regret it.