I agree with craft about ancestry.co.uk . You need to spend some time collecting information from your living relatives first to see if anyone has already done some work and aquired any civil registration certificates etc. I you know where your relatives are buried you could spend a while collecting information from their grave stones,
see the info under the 'articles' tab in this topic.
Also don't go mad and join everything..............different people on here will do look-ups for you. Dotty helps me when I'm stuck and I return the favour by looking at the 1911 census for her, as I have a subscription to it.
I started my tree on MyHeritage.co.uk which is free to get started......then someone suggested Ancestry was best...I changed and am still paying a subscription to them.
I wish I hadn't as I still prefer the Heritage site. I think it depends. They all have good points tho.