The Tiger Trainer .40 MkII and the World Models Super Frontier are both great choices for a glow trainer. The Tiger Trainer .40 MkII comes largely pre-built and offers glueless assembly. The control hinges are already installed and you can simply bolt together the wings and tail surfaces. The Super Frontier will require a bit more assembly, but nothing that you couldn't accomplish on your first airplane project.

A .52~.54 four stroke is a nice match with most .40-size ARFs. I like the Master Airscrew K-Series 12x6 for these engines, it's a wide prop designed specifically for four strokes and it really provides terrific thrust with an engine that can turn it decently. Your fuel economy would be outstanding as well, and 20 to 30 minute flights would be easily attainable if you managed the throttle well.

Thunder Tiger makes a very nice F-54s four stroke engine that your local hobby store should be able to sell you. The Magnum XL .52RFS (also sold as ASP or Sanye), the O.S. Max FS-52 Surpass (and the new 56FS-a), and the Saito .56 are all terrific engines in this size range. The rear-mounted carburetor on all of the popular brands of four-strokes might make them a tough fit for the stock engine mount included with whichever plane you select. If you're not up to replacing the supplied engine mount with a longer unit and possibly redoing the firewall blind nuts for the mount, you might stick with a .40/.46 2-stroke.

Good luck and good shopping!