Yes,You need to fill out form C100,and a C1a if you you believe there to be any risk to child. Forms available online. Print 3 copies and take down to your local court with the fee (which was £175 when I did it but may have gone up. form EX160A will tell you if you need to pay or qualify for reduced or none payment.
That''s correct, form C100. The charge is £200 now but can be waived if you''re on income-related benefits.
You have to fill in the form in triplicate, so I would suggest going to the HMCTS (Her Majesty''s Courts and Tribunals Service) web site. You can download a pdf file from there which you can fill in on the computer and print 3 copies.
You don''t need a solicitor to do this for you, the start of the process is quite easy, though you may want or need a solicitor further down the line.
Also, proof-read your form before you fill it in. Get someone else to do it for you. When I printed mine off, certain boxes that had been ticked didn''t print as ticked.