Hi,

"So I’ve been lying the whole day through and staring at this thing – and it gives me the creeps, you know."

Is this sentence all right grammatically? Yes, it's quite acceptable as everyday English speech. The dash, together with the phrases 'the creeps' and 'you know', gives it an informal tone.

The only thing I'd say is not OK in formal grammar is the use of the conjunction 'so', in a way that does not really join two clauses. I wouldn't say this can't be done in careful writing or speaking occasionally for stylistic reasons, but generally it shouldn't be done much. For example, you could walk into a room and say 'Dinner will be late' and people will say 'OK', but if you walk into a room and say 'So dinner will be late', people may want more information in order to properly understand what you are talking about. You'd be clearer if you said 'The cook is drunk so dinner will be late'.

Having said all this, in everyday casual speech it's not uncommon to start a sentence with 'so' in this way.

Best wishes, Clive