Break in training - how to proceed?

I'm running London in April and to date training going well.  10 days ago did a 15 miler relatively comfortably - then the weather struck!  With no access to a treadmill (not that I can run on one anyway) I hadn't run for 7 days.  Went out last night and was fine but this was only 5.5 slow miles.  My question is what long run would anyone advise this week?  Usually a break in training is due to injury and I know what to do in that case but this is new.  Do you just ignore the week off and proceed as you normally would - I was thinking 16 - 17 miles, or do you reign it in abit and go for less.  I may be over thinking the whole thing but I like to be prepared!  Any advice welcome!