If you decide to go to Tree house, use the Honiton Road park and ride which is next to Devon Heritage centre, download a map of exeter to use when you get there. To get back to your car, you get back on the bus at the stop where you got off, but check its the right bus, as other buses use the stop
If you want to go to Devon Heritage centre, check with them about parking, they had allocated parking, when we went, not sure what the arrangements are now, I expect they will be able to give you some instructions on how to get to them.