hancop,
I've had two SE's and I learned this on the first build. Yes, you will need to access the tank for maintenance. Some people have put a hatch in the bottom of the fuselage to do this, but I don't like adding a hatch unless absolutely needed. I feel (IMHO) they weakening the fuselage structure. On the SE you can still have access. When it comes time to put in the paper tube in the fuselage for the wing tube DO NOT glue it in. You can still assemble the wing with no problems. If you leave it unglued you can slide it out to get the fuel tank out. Also, before you put the tank in place use duct tape to make a "handle" on the back of the tank. This handle should be on the end of the tank with the tape going to over the sides of the tank, then use duct tape around the tank securing the sides of the "handle" tape. This little handle will let you pull out the tank if you need to access in the future.

Hope this helps