You'll be fine. Cats adapt quickly and settle into a routine.
Our cat (Milo) does the following with minor variations:
11.00pm to 5.30am - cat sleeps
5.30am - gets me up to feed him and let him out (no cat flap unfortunately)
7.00am - I get up let him back in
7.30am - Cat waits at the top of the stairs for me to fluffle him (A fluffle involves a good head scratch, neck scratch, under chin scratch, and general body stroking. He gives me no peace until he has had his morning fluffle !!

8.00am - The wife and I go to work - Milo sleeps until our return at 5.00pm.
5.00pm - Milo has finished the food in his bowl and demands a fresh pouch.
5.15pm - He goes outside and stays out for a good couple of hours
7.00pm ish - Comes in for playtime. My wife plays with him with string and cat toys.
8.00pm ish - He settles down somewhere either in the living room or on our laps (if its on our laps he is after more fluffle time!).
10.00pm ish - He goes out again and either stays out the night (if its summer) or comes in again around 11.00pm
11.00pm - gets in his bed and sleeps.
The routine does vary a bit (especially in the summer when he spends a lot more time outdoors) but thats basically it. They are creatures of routine and have amazing biological clocks. I don't need an alarm clock, he wakes me (never the wife darnit!!) at 5.30 practically on the dot. Tried to get him out that habit but he scratches and chirps and makes a right racket until he gets his way. (see Simon's Cat on Youtube!). That's Milo minus the baseball bat !!
