In reply to norrisdan71:
It'd certainly be fixable, the benefit of steel being its easy to work with on the grand scheme of bike frame materials. I'd be tempted to say it will be ok if the geometry is about right, more likely the frame flexed a lot and popped some paint off, and is slightly bent/buckled but not cracked and therefore unlikely to explode at random. I've seen a friend hit a huge tree head on (531 frame MTB), and ended up with his forks basically vertical, the bike still made it back to the car after another hour or two riding.
In the interim, you could scrape off the blistered paint and see if there are any cracks visible below it, and if you're still going to be out for a while cover the bare metal back up with some clear nail varnish or similar.
Vernon Barker has a pricelist, unsure how in date it is though! Looks like somewhere around £500 if you add up the new head tube, down tube and top tube prices. Certainly cheaper than a new frame, but not pocket change either! You'd probably be looking at another £100ish to have it stripped and repainted/powercoated after the repair as well.
https://www.vernonbarkercycles.co.uk/prices_frames.html