[Koha] Koha in school library

[Deb Vincent]

Hi all
I have cancelled my existing ILS to switch to Koha in our school library. 
Unfortunately I had to give a year's notice to terminate the contract, but 
on the plus side it gives me more time to set up Koha properly before 
making the switch.
So far, our IT team have set up Koha on the server, and I have been able to 
load existing students to the system.
My main difficulty is going to be importing our existing catalogue. I can 
export the basic data from our current ILS in an Excel spreadsheet, but not 
marc format. I know I can convert from Excel to marc21 using MarcEdit, but 
I am not yet familiar enough with the marc system to understand how to do 
this. I would be very grateful for any advice.
Also, is there any way of importing barcodes of existing holdings at the 
same time, or does this have to be done manually after the catalogue 
records have been imported?
Many thanks.