I don't know where in Scotland you are (it's a big place) but it's worth flying with Ryanair to Bournemouth rather than FlyBe to Southampton as it's a lot cheaper. If you are eligible for a Young Person's railcard, that'll help with the fares for the trains to and from airport to Swanwick. Even with an expensive hotel/B&B, it should be well under £200...
Can't help with the cheap B&B - I stayed at the Fareham Premier Inn (£65 a night) when I was down.