Where do I attach wires from heater (fireman switch??)

if the timer has the fireman switch attach the 2 wire to the heater and the fuse panel inside you will see a fuse with a yellow jumper wire ,remove the jumper and connect your switch

The connection point is not critical as long as the fireman's switch is connected in series with the safety loop. For instance you may cut a wire connected to the pressure switch and use two wire nuts to connect the wires from the fireman's switch, one to each side of the cut wire.

1) T101P201 timer does not have a separate manual yet
http://www.poolandspacontrols.com/products/mechanical%20time%20switches/pool%20and%20spa%20time%20switches.aspx

2) However typical T101P201 timer is ordinary T101 timing mechanism inside Nema 3R beige-colored outdoor plastic enclosure, with additional fireman's switch.
Wiring for T101 shows on following link, and shows on door of timer enclosure:
Check that your timer terminals match illustrations because many timers can fit inside Intermatic enclosures.
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T101

3) Fireman switch wiring:
T101P201 has a fireman's switch that wires directly to the pool heater thermostat.
http://waterheatertimer.org/pdf/Intermatic-Firemans-switch-156T4042A.pdf
If you are not using the timer for pool heater, or if heater does not have connection for fireman's switch, then do not connect fireman switch wires, and just tape them out of the way.

Add a comment for more information

You should upgrade to T104R201 240Volt timer with fireman's switch OR T104M210 (timing mechanism only that snaps into existing enclosure)
http://www.amazon.com/Intermatic-T104M201-24-Hour-Mechanical-Protection/dp/B0039Q3QRQ
http://www.smarthome.com/42657/Intermatic-T104R201-208-277V-Pool-Pump-Heater-Timer/p.aspx

T104R is 240Volt analog timer in Nema 3R indoor/outdoor enclosure without fireman's switch.
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html
Other resources:
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#pool
http://waterheatertimer.org/pdf/intermatic_pool-controls_sell_sheet.pdf
http://www.poolandspacontrols.com/products/mechanical%20time%20switches/24-hour%20mechanical%20time%20switch%20mechanisms%20with%20heater%20protection.aspx

Add a comment for more information.

Check that your pool heater supports optional fireman's switch
Black wires on firemans switch connect to pool heater. Power to fireman switch comes from pool equipment and not the timer.
If pool equipment does not support fireman, then cap off the wires.

Fireman switch turns off heater 15-20 minutes before turning off pump.
The purpose is so pool equipment lasts longer.

You can buy the fireman's switch separately, but if this is new timer, then switch is probably good.
Open following link to identify fireman's switch and related parts for the timer:
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#fireman

Upvote the help.
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.

Typically the intellitouch controller is wired to the "fireman" switch on the heater. If the switch is not closed the heater will not turn on. If the heater was wired to the controller through the power supply rather than the fireman switch and the fireman switch is not bypassed at the heater the problem you describe would be created.