Also see if you hospital do any twins sessions - it was v useful to meet the midwives/ talk through the process and we got to see the NICU/SCBU so that if there was an emergency we'd feel a bit less scared.
Agree the TAMBA course is helpful from a practical perspective,not so much from a friendship perspective. Worth doing though.
I did a TAMBA one in Guildford. As 12Legged said - it was great for practical facts eg C-section/Neonatal that you don't get with NCT/NHS. But it was a v wide catchment area so we didn't stay in touch. NCT one was light on useful info but I still see all my class.
Couldn't find any near me. If there is one close to you I would recommend it, especially if they are your first. This is not cus you will learn anything you won't pick up anywhere else, but because it might give you some other local twin mums to stay in touch with. The only people I have been able to really talk to about handling twins and a toddler are friends I have made who are in the same boat. It is just different, and those that have experienced it get it.