Mature Student Applying for Medical School

I wondered if there's any mature students out there with advice for applying to medical school? I won't be applying for a year or two yet as I am currently working on a masters in archaeology and possibly doing another masters in psychology as well as brushing up on my science in the meantime but was curious as to whether having a masters degree is a good starting off point? I also have experience working in healthcare as well as working as a psychiatric support worker so have worked in a hospital environment.

I noticed people mention the UKCAT--is this a necessary thing to complete for attending medical school? There's a ton of information out there and I have only just started researching the possibilities.

I'm from Scotland and will not be relocating so I'm hoping to attend the University of Aberdeen. I am a little worried that I will be the only older person (I'll be in my late 30s by the time I'm ready to attend) but I don't want to let that stop me.