How to leave?

I was checking my diary the night before last and, since I began this enquiry process, it contained an unusual sight. Nothing. Yes, nothing to do this week.

That's good. I'm tired for no apparent reason other than it's getting darker. A week of no meetings/visits etc is just what I need. I know it'll be much busier in ministry, but I work full-time with an hour commute each way on top of my working day.

That said, I enjoy leading worship. I've starting to feel "wrong" sitting in the pews, not being involved. Well, not all the time, not on holiday, but definitely in my placement church. So, I contacted my assessor offering to help lead worship - specifically write and lead the prayers.

She's happy for me to do so, but in her reply mentioned she didn't get a chance to speak to me on Sunday. I always stay for coffee (well, in my case tea) and try to speak to new people (a lot of them are new to me, but never mind) or those on their own. Sunday was no different. Many people wanted to see my assessor and, when I was leaving, I couldn't get a hold of her to let her know. She mentioned I should even if she's busy.

I feel really rude interrupting someone. I also know people want to speak to ministers in confidence after a service, so I don't want to intrude on that. So, how do I politely let her know I have to leave without appearing rude to those speaking to her?

I can't stand the whole "sorry to interrupt, but" statement. If you're so sorry, don't do it. It's up thee with "no offence, but" and then goes onto be offensive. Maybe it's just me. Or should I try "excuse me, I'm just leaving now"? I must remember to ask about this at my next meeting.