OK here hopefully this will help. The Apprentice 15e can be purchased as RXR, where you add your own receiver. Get a Spektrum radio, either the starter DX6i or a DX8, Choice depends on capital, the DX6i can store 10 models, both aero and heli.  All BNF planes work with the DX6i radio. If you want to get a parkzone flyer BNF, you already have the radio.

What i did was get an Eflite T-34 Mentor, it comes with the DX6i radio, then I got the Apprentice and added an AR600(?) RX to it. I also have a UM T-28 and UM Corsair along with several micro Helis on the same radio.  Since none of my planes require more than 5 channels I am all set.

The Um T-28 is a great little flyer, and binds well with the DX6i, and gives you the ability to adjust the settings, give exponential to the controls, dual rate it, mix it, do whatever you want to make this little bird do some crazy shtuf.  I learned to fly with that one, then moved on to the Apprentice, and flew that one right from the start, take off land, without any help, in my back yard too, of course my backyard is 5 acres, but I still have fences to avoid.  It is a great flying plane, I highly recommend it to anyone who asks.

  The T-34 is also a good flying beginner plane, but on this one I do recommend an instructor since it is a bit more aggressive in the air than the Apprentice, but very stable and self correcting.  It is a progressive trainer in that you can remove the training wheels, what are otherwise known as wing droops, and the plane is quicker and more responsive, but can also wing stall so you definitely want to be good at flying before removing them.

Any way you look at it, you are going to spend money, so might as well get your moneys worth. You can get the RTF UM t-28, and the radio it comes with can be used for other micro BNF, may even work with the parkzone T-28, but to do so you would have to bind  every time you switch between planes.  Or you can spend the money upfront on an RXR Apprentice  and DX6i radio set, and have when you need for the future.

For the Mentor, $499 with DX6i,  The Apprentice PNP $229, DX6i $209, Together $438.  Apprentice with DX5e $299.

The DX5e doesn't store models, so you would have to rebind when you switch planes, and reset the controls. So can you use the one radio with other planes, yes, but you have to reconfigure it every time.  So there you have it.

Been there, done that, have the receipts to show it.