Umm personally for £1200 I would not risk it.
The half an inch is not to bad as its half inch split both ways so its only 6.25mm further towards the arch on both sides than your current rims.......I would say its the 19" part that would be the
problem.........and you'd need some stretched tyres like a 215/35/19.......which would mean your ride would be crap
I'm not saying they won't fit but it would definatly be bloody tight if they did
Any chance you could try them first?