I just checked out the plane you got and am also a relatively new pilot (2 years)
Heres a few things I would try.
this plane should be able to take off without that rear wheel even on, adding a larger one will put the CG back even more!
those front wheel "spars" look to be too springy, this will push the wheels out and make them not roll straight.
my first 4 channel plane did this too much lift then sharp bank to the right and fall out of the sky trick. this is what fixed it for me, the cg's on these asian sourced planes I have found to be incorrect. mine was incorrect as when I checked more thoroughly, the cg was for a brushed/nimh setup , they them throw a brushless motor (lighter at the front) and a small lipo battery (lighter in the center) and leave the cg the same on the manual......
the next thing for me was the motor mount. mine was plastic so I had to shim it with washers.
it needs to point 6 degrees down and 2 to the right. If it is level or up it will pull itself up into a stall and fall out of the sky.
If it cannot pull itself along with that motor on the ashphalt there is something grabbing. bend the wheel 'spars' springs whatever you call them so the wheels are straight up and down and pointing exactly forward to reduce drag.
That little b'less motor should easy pull it up, I have used a few similar ones.
When you meet your experienced pilot, ask him to fly it and tell him he is not responsible for anything and not to feel bad if it does the same for him and falls out of the sky as this is learning and you need to find out if it is the plane or the new pilot.
Does your radio have expo or dual rates? this is a huge advantage for new pilots to turn down the thumb speed! if not, make sure your control rods are on the slowest point of attachment on the horns.

this high wing should taxi straight, then take off and float without input if it is setup right and you have a long enough runway.

personally, I woudl recommend putting on the shelf, buying a multiplex easystar 3 channel, get used to flying without wheels and ailerons so it is fun. then when you can take off, land and have fun with it confidently. get the 4 channel back out!