Mortgage with Poor credit rating

Hi

I would really appreciate some advice/guidance on an issue I have.

Me and my partner are looking at buying an house together but I'm worried with regards to my Credit Rating.

I have two defaults on my rating, both satisfied in 2009/2010.

I have conducted my accounts good since these. But rating still showing poor. Even though all the accounts are upto date and have been since 2010. I have no loans, only thing I owe is £300 on a store card and a credit card.

I know alone I would have no chance of a mortgage, but hopefully the following will help with a joint application:

My partner has an excellant credit rating with a 50% mortgage on our current home. 50% equity.

We have a 67% cash deposit for the new property so will only need a 33% mortgage.

We both have full time jobs earning £42k a year combined.

The only debt my partner has is his mortgage which when we sell the current property will be paid off.

Please can someone advise me on whether my rating will be a problem with the size of the deposit and how much we want to borrow?

Thanks in Advance :D