Trish,
The doctor will likely have his own set of recommendations, but to plan in advance I attach a link to a website with generic information. This website is very close to MY doctors recommendations - follow your doc's directions, every doctor seem to have his own list.
Pressure on the bladder is to be avoided, as you noted. Be prepared to deal with constipation if it happens - lots of liquids, and bland meals helps. Any over the counter med needs to be cleared by the doctor IF there are other medical issues that need to be considered.
Being too active, forcing a bowel movement or any "straining of the lower gut muscles can cause pain and perhaps some minor bleeding. You should receive instructions about when to call the doctor if there are any concerns after the TURBT.
Most TURBTs go smoothly with no problems. My one exception was heavy bleeding 3 days later that did require a trip to the emergency room. Make sure you know who to call 24/7 IF there are any questions.
A warm pad over the bladder often feel good and eases pain.
Everything should go fine. Good of you to plan in advance.
Best,
Jack
westcoasturology.com/mens-health/treatments-procedures/trans-urethral-resection-of-bladder-tumor-turbt/