147/99 would be significant if it were real. There is a high possibility that you do however have ' white coat hypertension
', this means your BP is only up when the doctor checks it!
Your GP has made the excellent decision to excude this with 24 hour BP monitoring, and you seem lucky enough to belong to a practice that has a monitor of its own, which will speed things up.
Once you have had the test your GP will be able to read through the results and hopefully reassure you.