You might want to consider a gaming chair. Not the armchair lazy boy style but the ones that look like office chairs. They are extremely comfortable as they’re built for sitting in all day. Our Health & Safety recommend them for working from home but unfortunately have set a rather miserly budget for me.
These companies got good reviews in my research.
https://secretlabchairs.co.uk/collections/titan-series
https://www.noblechairs.co.uk/