Thanks for replying, Canders. Good to know 15 hours a week should be ok. 3 hours' work per 1 hours' lecture would work out at 33 hours for me! Hopefully it's not going to get to that stage quite yet.

Thanks! It's nice having it all set out on a timetable now - before I've been thinking "today I have to do this and this and this and this and this" and it's felt like so much that I didn't know where to start. And by working until half 9 instead of 9 I get to do half an hour's violin practice as well, so that's that problem solved.