Many thsanks for your reply! At least I now understand that TM Espana is Moviestar which is good to know!!
Last night I used my THREE MOBILE 'hot spot' mifi device, and it worked ok in Central Menorca in Es Castel
For some reason it does not seem to be as stable as the Moviestar dongle (which is fitted to a TP-Link wireless router), here in S'Albufera (just outside Mahon)
Anyway, from your great site, it looks as though my best value, when I return next year is to buy my Three Mobile 10gb sim for £15 in the UK (around 20€) and I will invest in a TP-Link wireless router to use in Menorca.
The only reason that 'unlimited access' is appealing is that my main use (while on holiday) is streaming UK BBC radio programmes, and also obtaining NETFLIX and BBC I-PLAYER. Both of these use a lot of capacity as I am sure you know.
Also a tip for your followers is that SPEEDYTV is a fantastic VPN provider. Unlike HOLA which is free, they chrge around 10€ for 30 days, but it is a very proffessional setup and works first time, unlike HOLA!!!
Just as an 'exercise', I will transfer my Three sim to the Moviestar dongle, just to see if it works?
Many thanks again Wolfbin for your help!