Hmmm….I hate banks…why 30% FFS?!
Sort of because of what happened just the other day, when the banks went into financial meltdown and the whole world almost stopped turning on its axis because they had lent too much money at too high a risk against properties that were over valued by a populace that had failed to grasp the concept of three times your income on a mortgage.
We can't have it both ways; we can't expect the banks to make high LTV loans(aka risky loans) when it suits us and then pillory them when it all goes wrong.
OK so now off the soap box (and I do sympathise with your situation), 30% as a deposit is pretty common these days, but are there not some other deals at say 20%? That's still a decent amount although you should expect the rates to be higher as a result, probably by around 1.5%.