Once you move over 70% the mortgage will have to be OK'd by the Mortgage association (can't remember their exact name). So even if the bank is willing to lend it could still be vetoed by the mortgages asscoiation (that is my understanding).
You will never get this type of mortgage on a village property, it is normally only available on specific types of property such as an apartment in a managed complex.
Also, once you take on this type of mortgage you are legally bound to pay an insurance premium, which basically covers the banks investment in your property. I think this is equal to 3% of the property value? Need to check though. The important thing to remember is that this premium covers the bank's investment and not yours.
Your best bet is to just go to the bank and just ask, they can do a free evaluation on the property (as you will already know being a property owner) and discuss feasibility given your monthly income etc.
P - 2.75 is the rate we got. Seems reasonable to me. Not sure that fixed rate mortgages are available on 90% lending. I know for a fact that some 'offers' - such as no penalty for early redemption, bi-monthly payments, ability to pay off lump sums etc do not kick in until the outstanding value of the mortgage has dropped back to 70% or lower. But this may just be HSBCs policy (with whom we have our mortgage).