You may not like what you are going to hear but there is a very sneaky scam where the developer "pays" the stamp duty to get the price recorded as higher at the land registry and so the bank thinks it's lending you money on a property that's worth a higher figure. The solicitors and sellers colaborate in it to make the deal more tempting and even though it's not illegal, it's not really the right way to go about things.

I'd be inclined to go and check everything again if you do so free of charge or for pennies because the last thing you want to do is to get shafted.

They shouldn't be charging you for the other parties fuck up though and if something comes to light later on you'll be in the mire so I'd make sure the solicitor is jumping through a few more hoops to give you some peace of mind, if something is amiss and you've bought the house, who's going to cover up the shortfall if they've built it an inch too far to one side? Or if there's going to be a motorway planned to run through your back garden in a few years time? Or if there is someone else who has access rifts of way a Ross your property which means you can't build that extension/garage you were thinking about?