Chair advice (for one that often fidgets and sits on a leg)

[trif55]

So I've not really solved the chair thing, I spent years growing up on one of those 80s style bucket chairs with 4 wheels and tended to sit cross legged, or at least with one foot under my other thigh, I've got an old SFF pc under my desk as a foot rest but I think I need something higher or that I can adjust because I'm certainly not comfortable sitting with my feet flat on the floor for any length of time. what's everyone's advice on footrests?

 

Since then I've been on a gaming chair at home and a reasonable price office chair at work (back of it pivots and the seat slides if that makes sense) neither is great for any length of time and I end up fidgeting a lot, what kind of chair do I need for someone that can't get comfortable on a normal chair? will the footrest help? I tend to get numb patches, is that just bad chairs? Is getting a used Herman Miller still the best option?

[trif55]

HM's seem harder to get in the UK, is there any UK equivalent ?