Do I have to join the pension scheme?

No, if you want to you can refuse to join, or leave at any time. However, for your employer it is legal to:

• assume you will join unless you actively opt out
• require you to discuss it with somebody first, and get you and your spouse to sign a document to say that you realise what you are giving up.

It is almost always a good idea to join a workplace scheme, if the employer makes a contribution towards it. If you choose not to, you are taking an effective pay cut, because you will lose the employer's contribution.