You are welcome. :-))GRO is The General Register Office.
Start by writing down everything you know, look for gaps in the information you have, and fill them in by BMD certificates etc. It's a long but very rewarding process and you need to verify everything as you go along or you may find yourself researching the wrong family.
You can write (email) for application forms( state if B or M or D required,or get a few of each) thet will be mailed to you and you can fill them out and send them in and they will mail the requested certificate to you, or you can order online. I used to do that but they now have annoying credit card procedures(via worldpay I believe) which is not customer-friendly, so I stopped doing that. I imagine as you are in the UK you will have other options open to you to get your BMD certificates. They are in Southport. FAQs http://www.gro.gov.uk/gro/content/certificates/faqs-birth-death-marr.asphttp://www.gro.gov.uk/gro/content/certificates/faqs-birth-death-marr.asp