Yes I think you are!
Getting a new manifold in the UK is virtually impossible. Stateside, and then only original Ford Performance, M-9424-P46, not Dorman (Amazon/RockAuto etc.), if you are sensible. Get the gaskets at the same time. Manifolds are difficult/impossible to repair, and second-hand ones are very rare, and generally not to be recommended.
Just the gaskets from Brown & Gammons at https://www.ukmgparts.com/product/r7...each-lkj000080 , or DMGRS at https://www.dmgrs.co.uk/products/mg-...anks-lkj000080
... more important though is to get your full membership sorted out, since I just noticed you still haven't done that, and not being "green", will be unable to read most of the vast amount of advice here you obviously need, in threads which are closed to you. Same applies to your questions in post #11, I'm afraid.
My £50 MGOC renewal just plopped through the letter box, obviously far from welcome, but worth every penny for the full Two-Sixties access.
David