cas wherever you subscribe you have to pay for certificates as these are from the governments registrar's office.
I belong to 4 sites which is a bit OTT but I do family trees for people (not for money) but I do charge them for any certificates they want but it's just a hobby for me. Dot is an expert, I am not. Another very good ABer on genealogy is Barmaid.
I belong to Genes Reunited, which is a great tree builder, plus it has a good community board and chatroom...this only costs about £9.00 every 6 months for a basic membership
I also subscribe to ancestry which is my favourite as they have a lot of other peoples' family trees which tie in with mine, plus a very good filter search.
I subscribe to genealogist but am thinking of not renewing my subscription there but it is good for trawling through actual records as opposed to accepting records others have interpreted.
I also subscribe to findmypast as they are brilliant for overseas and military records and also have the 1911 census.
If I were serious at starting to research my family tree I would subscribe to Genes Reunited for actual tree building and ancestry for the research.