Hi Kirsty
Firstly welcome to the forum.

A couple of questions firstly - what date did the company incorporate/date started trading and what date is the year end? Were date were these invoices? You will need to key these invoices in exactly the same way as normal, ie set up suppliers/key to appropriate nominal code (be it expenses code or assets etc) BUT the date is key in sage - so let me know the answers to the above and I will explain.

Other side of that is of course payment of those invoices - have they gone via the business Bank account, or indeed been paid for by the Director personally? If the latter I can talk you through that too.

Re the C79 - this is the import VAT that you are to re-claim for an import from outside the EU. Where out of interest? What you need to make sure you have are the invoices from the company who have exported the goods (key as supplier in the normal way). You may also have an invoice from a freight company/courier/agent - depending on how the goods where brought in. This invoice will show the import VAT, but you cannot claim the import VAT back using this invoice - you must only do it from the C79. Care this freight company invoice will also have other charges on it as well.

NB You cannot claim import duty back, only import VAT

You will need to set up/amend a couple of nominal codes in sage as follows:-
5101 names import duty
5103 import VAT
5105 import fees

You need to set up the freight company as a supplier, then enter the invoice as follows:-
Import duty element - key to 5101 nominal £xx T0 Vat nil
Import VAT - key to 5103 nominal £xx T9 (So it doesnt appear on VAT return)
Import/admin type fees - key to 5105 nominal £xx To or T1 depending on what the invoice allows JUST for that fee.

Always check that the VAT on such invoices is reported on the C79 and that all info on the C79 belongs to your company (and that you actually receive the C79 in the first place as its posted by snail mail by HMRC!!)

Keying from the C79 is as follows:-
Journal entries
Debit purchase tax control nominal code 2201 £xx (ie amount of import VAT shown on each line of C79 should match the above freight company invoice) NB T1 this (THIS will ensure the VAT re-claim is on the VAT return)
Credit import VAT nominal code 5103 £xx T9 this

Take great care re T codes used.
The Import VAt nominal should only ever have a balance in it that represents the C79s awaited.

I would suggest you have a read of the import process on HMRC's website, plus the section about C79s and especially what to do if you dont get the paper version in future.

Can I also suggest in future that you do separate posts on the forum for separate questions  (several reasons - some people wont answer if they feel they cannot answer both questions so you could end up with no answers!  Or some people would ignore the C79 question due to heading mentioning sage as they dont use sage)

Hope that helps

Chat later once you have the answers.