My front dental cap broke in half and I used superglue to fix it will my dentist be able to get it off?

I wouldn't worry; your dentist should be able to get the broken piece off and reaffix it properly when you get back from your holiday. In the future, if this happens again and you don't have access to a dentist, you can visit a pharmacy and they should have temporary dental cement that you can use, rather than superglue.

Many patients part way through treatment have this dilemma. I can not actually say the official temporary cements are actually very good, because they often contain a chemical called Eugenol which actually prevents the final (cap retaining adhesive) from bonding as tightly as it would have otherwise done. 
That is a problem often when dentists re-cement temporary crowns. The standard (low-cost) temporary adhesives, all have this compound in them.
Simply because of this, with larger cases, I send the patient home with the correct temporary adhesive, if only to help their emergency dentist to do right by them. 
Good luck and hope that your treatment has not been derailed too much -
Super glue is on there now, but let your dentist now, she / he may take a new impression, inc area the temporary breaks as it is being removed frown d your mouth. 
Good luck and speak to your dentist soon. -
Kind regardsThomas Dey, BDS, MSc