Update
I am sending the TP Link repeaters back to Amazon as they didn't make any difference to my set up. In fact over a few days testing at different times of the day and at the same time of day that I installed them originally, if anything performance was worse.
I have now installed a couple of BT Discs kindly given to me by a member on here, and these work superbly so I no longer have poor connectivity near my Hive stuff.
Thanks to all who provided input, much appreciated.