GPS mapping of land for Land Registry maps

I've agreed to sell a couple of small part fields and need to get them mapped for the documents.
The old fashioned architect woman who used to do these by triangulation has retired.

To quote our builder 'Is there an app for that?'

Can land agents etc get a map out of their handheld Trimble thingys? 1:1250 or 1:2500 would suit?


Thanks