Liability for changing percentages of tenants in common?

Hey everyone,

My girlfriend and I have just bought a house (which is our primary residence) and we are registering it as a tenancy in common with both of us owning slightly different percentages as we put in different amounts of money. We have quite a lot of work to do to the house and would like to change the percentages we own once this is complete (probably in about a year) to reflect how much money we have put in (at this stage we're not sure exactly how much it will be or which one of us will pay what). My solicitor has said that we can change the % ownership of the tenants in common in about a year when we know how much it should be. My solicitor has said that changing the percentages creates no tax liability and that if all we're doing is changing the % that each of us own then we don't have to pay any stamp duty or any other type of tax. I just wanted to confirm this is correct as (my understanding is) normally if you transfer an asset to someone else then they would pay Stamp duty on it based on it's actual value, which would make me think if we changed the percentages from (for example) 60/40 to 70/30 then stamp duty would be chargeable on the 10% that was transferred. I'm assuming he's correct as he seems to know what he's talking about but I just wanted to make doubly sure that we weren't opening ourselves up to any tax (or other) liability by doing it this way? FYI we are not married or civil partners and want to own different percentages which is why we haven't done a joint tenancy. Am I also right in saying that as it's the primary residence of both of us when we do sell it (assuming it's still our primary residence) then there won't be any CGT due irrelevant of what percentages we own?

Thanks very much,

Dave