Buying a property that lacks building regs for recent work

[rootsnall]

The property is really good otherwise, hard to let go.

Is it really that desirable ? A one off ? Have you got any builder mates/contacts who you can take round and get them to take a look, and you are further look. You are likely worrying about nothing other than having to deal with the same issues if you sell down the track and an indemnity will probably get you round that. Worst case scenario the steel can probably be replaced for a grand or two ( and a load of mess ). The extension footings you'd have to live with, if it's not moved yet it probably won't. If the sellers or EA are awkward about further access then walk. With the stamp duty change coming you are probably in a strong position to get money off.