Buy the h2s. Installing a pre made backup build brings in all the settings. So disable tuner B after installing wooshbuild.
With a single cable you cannot watch one program and record another. Therefore why don't you upgrade to a dual cable. Its cheap as chips.
Check your existing LNB on your dish. Is it a single, dual or quad. If more than a single just buy a twin coax cable with fconnectors off ebay. about £7
If your LNB is only single just buy a new sky quad LNB. about £10. They are easy to install. Just make sure you don't nudge your dish when you do.