I'm sure it's fine as a one off hun but it's not such a good idea!
Try to make time to grab something, have some standby meals in the freezer or make a big batch of pasta or rice salad or something to last a few days, or make more dinner the night before so you can have left overs!
But yes, it's okay, I don't think you'll be very full though....
you could have up to 3 hi-fi bars a day, two as a HE and one as syns. however they are not there for meal substatution. however as this is a one off, it's fine. try to find some fruit or something though if you can.