Head Gasket query

Hi,
I think my 2003 Jimny might have a head gasket issue - Noticed it wasn't running right and was stalling when coming to a standstill - it's an auto and then noticed what I thought was smoke from the engine and the temp gauge was maxed. I was able to quickly pull over as was near home.

On inspection the radiator overfill had shot off its mount (cap was still on) but it was empty and when it cooled its seems rad was empty. Filled up radiator and when I fired it up after a short while lots of white smoke from exhaust and engine was missing (unless revved over 2k - coolant leak into cyclinder?) on that basis I figured head gasket although temp hasn't crept up since but I have not run it longer than a few minutes as didn't want to rick causing any further possible damage. It's going to be looked at my a mechanic just to be sure as I know naff all but the question is if indeed its is the gasket, are the kits easy enough to get, is the head/block alloy will it need special tools to complete the job, these were asked by my mechanic who hasn't done one of these before.

Also, last year I had to top up the coolant on a number of occasions and there was a bubbling sounds behind the dash and temp was very high so wonder if this could have been a coolant system issue all along and got worse?

Many thanks