Are part-time jobs allowed during funded PhD programs or are they strictly full-time in UK?

Yes, you can take on part time work during your funded UK PhD, but you are not free to work as much as your visa technically allows. Your funding body, your visa status and your university each impose their own limit, and in practice the strictest one wins, so you need to check all three before committing to any job.

The Three Limits That Apply to You

What You Cannot Do Regardless of Hours

• You cannot be self employed or freelance under your visa.
• You cannot fill a permanent full time vacancy.
• You cannot work as a professional athlete or entertainer.
• Self funded students can work up to the full 20 hour visa limit in retail or hospitality without a funding body restriction.

My Advice

Talk to your supervisor and funding office before accepting any paid work, since your funding terms will almost always override your visa's more generous 20 hour allowance. If you are self funded, you have more flexibility, but still declare the job to your university to avoid jeopardising your academic progress.