Will I have issues using my UK-issued 60-day tourist visa if I do a border bounce into Thailand?

I applied for a 60 day tourist visa in the uk but unfortunately it wasn’t granted in time for my flight so I’m currently in Thailand on 30 day visa exempt which I’ve already extended. I plan to do a border bounce in order to use the 60 day visa and I’m just wondering if doing so will create any issues due to the fact that the visa was issued from the UK embassy but not flying from the uk when I use the visa?

Also, I was planning to drive to the Malaysian border and cross there and back same day if possible , does anyone have any experience of doing it that way and can offer advice which crossings to use/avoid, can I cross on foot or need a bus etc etc?

Many thanks.