The Happy Accountant

Every company director has a personal responsibility to make sure that the company files its statutory returns to Companies House on time.  Directors can be prosecuted if they fail to do this - and it’s a criminal offence, so if you are convicted, you will end up with a criminal record and possibly a hefty [...]

Pretty much anyone can form a company.  It’s preferable to be over 18, but it’s not obligatory.  However, you cannot form a company if:

you have been disqualified from being a director (while the ban is in place).  Companies House holds a current register of disqualified directors. 
You are an undischarged bankrupt (except with the courts’ permission)

Essentially, before you begin, you need:

a company name, which can be almost any name that has not previously been registered.
a Director
a Company Secretary (which cannot be the sole director)
(or you could have two directors, one of whom could also act as Company Secretary)
a shareholder (which can be either the director or secretary)
a memorandum of association
articles [...]