Yes, "R" is recall, which does a flash on the line when pressed. When you hear the call-waiting beep, if you press "R" it should place your current call on hold and answer the second call. Press again to switch back to the first call.
On a basic telephone you can do a short flash with the hookswitch for recall, but on some electronically controlled phones, and just about all of the cordless variety, you can't hang-up and pick-up again fast enough for it to work.
The flash-for-recall on the U.K. network has a maximum allowable period which is considerably shorter than in the U.S. If using the hookswitch, it really does have to be just a very quick press-and-release, like pressing a number digit when dialing. Anything longer and you will disconnect the current call. (If you use an American phone here which has a "flash" button on it, it will quite likely open the line for too long resulting in disconnection.)
Although probably not relevant to your particular situation, you should also be aware that some phones have two different settings for recall operation, often set by a small switch on the back or base of the phone, or in a user menu. The option you need for these is "flash" or "time break" recall. The other option - "earth recall" -- is used on older PBX systems in offices etc.
You can find a user guide for your phone here:
http://www.binatoneonline.com/manual.aspxAnd finally, the codes for controlling call waiting here are #43# to disable and *43# to enable. *#43# will tell you whether it is currently on or off.
