Do you mean the Samsung DVD-VR500E? The following steps should work for most DVD recorders. (In the US, you use the AV Input with an RCA composite cable or the RF input.)
If you get a digital-to-analog converter (set top box) and your current antenna provides the OTA signal at your location, then yes you will be able to record a digital program. Connect the set top box to AV1 or AV2 (the SCART inputs). Then use the Input Sel (under PR mode) to select the input. (Alternatively, connect an RF modulator to get the signal to the coax input from the STB to the recorder.) See page 75 of the manual for the DVD-500E for details on setting the input for recording: http://downloadcenter.samsung.com/content/UM/200410/20041023105238671_00500A-VR300E-XEU-E-B.pdf
. Some DVD recorders only record on the TV (coax) input. In that case, you
will need a set-top box with a RF out or an RF modulator but you can
still record the digital program.
A dual tuner set top box will let you watch one program and record another if both the TV and the recorder are connected to the STB. If your TV has a digital tuner, you can split the incoming antenna signal to go to the set-top box and the TV. (Then you can also watch one program and record another.)
I prefer to use a switch instead of a splitter to reduce the signal loss. However, this forces me to record the program that I am currently watching. Since most of my recording is for time-shifting, this doesn't cause me a problem.
This site, http://www.ricability-digitaltv.org.uk/pages/products/stbs/stb_search_results.asp
, has a list of reviews of set-top boxes for the UK. I know in the US, it is harder to find new converter boxes. However, they frequently show up in the used market as people replace their older TVs. This may apply in your region as well.
I hope this helps.