Hello again
Hope you had a good holiday.
You don't say who your grandparents were but, as a rule, anything relating to births, marriages and deaths after the beginning of the 20th century is not always easy to find on the web.
My first option would be to try the freebmd site which does sometimes give dates up to about 1920ish. If it's after that I am afraid it means trawling through the bmd records at your local archive office (I think some records are kept at local libraries but I have never tried that route myself).
The way I would do it would be try to see if your grandmother remarried, starting soon after your grandparents separated. I believe there may be a way of finding out about divorces but, again, I have never tried to find out anything like that. If you do find a marriage that seems likely you would probably need to send for the certificate.
Another alternative would be to buy a subscription to either findmypast or ancestry (both around £80 a year I think). The basic package on findmypast gives access to all censuses except 1851 and 1901, but you would be able to scroll through the births, marriage and deaths quarter by quarter and year by year up to 2005/6. I think Ancestry would probably give you the same options and they do have most of the 1851 and 1901 censuses.
There are a lot of kind people on this site who might be willing to help but you would need to give quite detailed information because of the time factor involved in looking up information when it is not in a census.
Any local archive office should have the bmd info for the whole of England and Wales up to at least 2006. Some are willing to look things up for you if you are unable to visit but they do charge, usually by the hour so it can get quite expensive. However, local archive offices only have parish records for the county they are in and they do not receive the records until the parish books have been completed so not all records are available as some books are still in use by the particular churches, especially if it is a small parish.
Sorry not to be more helpful.
Delta