FTB mortgage, help please!

We are first time buyers and have 20% deposit. (Currently renting)

Before we started looking for a property we saw a few mortgage advisors who took a few details from us and confirmed that on our current salaries we would be able to borrow the 80% needed, subject to a credit check.

We have been looking for a property for ages and have finally found one and put an offer in, which has been accepted.

So we went back to the mortgage company who would give us the best rate, and started to complete a FULL credit check, etc.

We were then told that due to us leaving the country for a gap year, we would not be accepted by ANY company for a mortgage, and would have to reside in the UK for a minumum of 2 years before being accepted.

We are UK citizens, have lived in the UK all our lives, we simply went abroad for 18 months to work (and ironically save up for a deposit for a house!)

So, we have to more fairly quickly on this. The mortgage company who we went to for the credit check has sent in an 'appeal' with all the details of our circumstances.

Does anyone know of any company who would lend a FTB who has lived abroad and then come back? We are both in full time employment.

Any help is much appreciated.

Thank you