Well, I'm here but I'm confused!
Simply entering details of your journey into here
http://www.nationalrail.co.uk/
will bring up all train services using recognised routes. (i.e. ones where through ticketing is available). Fares are also shown.
Once you're presented with a list of options, placing your cursor over the number in the 'Chg' column will provide you with details of how the changes work out. Alternatively, if you click on 'Details' you'll be able to see which train operators are involved. Further, there's the facility to 'show calling points', which can be useful if you might want to consider boarding the service further along the line.
This map shows main rail routes, together with train operating companies:
http://www.projectmapping.co.uk/Resources/TOCs%20v40%20Aug%202017.pdf
If you want all of the detail, use this map (with quite a lot of zooming):
http://www.projectmapping.co.uk/Resources/TOCs%20AS%20v27%20Aug%202017.pdf
If you only want National Rail routes around London, here's your map:
http://www.projectmapping.co.uk/Resources/TOCs%20AS%20v27%20Aug%202017.pdf
If you want both Underground and National Rail services around London, see here:
http://www.nationalrail.co.uk/London_Rail_Tube0517.pdf
If you think that you might need a bus at either end of your journey (or even in the middle of it), simple enter your start and finish points into this travel planner (even if they're nowhere near to rail stations) and it will combine both bus and rail travel for you:
http://www.traveline.info/
If I've still not answered your question, just tell me where you want to start from and where you want to end up!