Hi there,
There is a lot that can be done without spending out too much although there are certificates or their equivalent that you really do need to see for confirmation, otherwise there's too much guesswork involved.
I'm sure you've already realised that many censuses can be looked up by the generous people on here, also usually you can access Ancestry.co.uk for free at many libraries, but when it comes to finding out the parents of the bride or groom or child, that's when the confirmation is needed.
If it is at all possible for you to go to your local Record Office - probably in the main library - you might be able to find many marriages and baptisms which will give you exactly the same information as a certificate will and so save that vital £7 on each occasion. The Record Office also holds microfiche copies of the BMD indexes.
My main suggestion is that when you do discover the Parish Register where a sacrament took place, try to spend a while searching for more of the same name and take careful note of the dates you have searched, then you are building up your own database and you are bound to find out that they are connected somewhere, even if it's not immediately obvious.
Once you've got past the dates of censuses, investigate what other documents the Record Office might hold, land/rent registers, freemans registers, maps etc.
If you aren't close to the Record Office, then check to see where your nearest LDS Centre is, ordering films from them is relatively cheap and again you should be able to search a number of years on one film.
I'm sure there will come a time when you absolutely need a certificate - think about asking for them for birthday and Christmas presents from friends and relatives.
Hope this has given you some ideas.
