Having spent some time trying to sort this out today, I have found the following:

- Only Vodafone offer a true Multi sim to new users, however only on old tarrif scheme and it was very costly, it is also very basic and means if you are using MMS or GPRS or Tri-band features it wont work. It will be a phone and thats all

- Both Vodafone & Orange can offer multi sim to existing users but see above

- Buying a pay as you go number and diverting your main mobile to this number is a great option for incomming calls but ofc very expensive if you wish to make outgoing calls (like me).

The solution I have taken is to add another number & seperate to my existing tarrif and swallow the additional £13.50 line rental per month.

Kinda sucks to be honest but the most cost effective solution I could find with Vodafone.