I have been running a "pro compact" or 36/52 on my bike for the last few years. I've just bought a "new" bike (eBay bargain) that has come with a compact 34/50. I'll be using my old bike as a winter / wet bike so ideally would like to match up the gearing. How easy a job is it to do myself? Is it as simple as swapping out the chainsets? Do I need to adjust the front mech? Any advice appreciated.
Assuming you are doing a straight swap of the chain sets John, everything will depend on their type and age. If they're both modern and threaded the job is easy, with no special tools required apart from the bottom bearing cap spanner. Shimano make 'em for a fiver and they will usually fit most Campag' caps too. Watch a YouTube video on the subject - the Park Tools films are usually good - and off you go. You should be finished and drinking tea in an hour, including the necessary dropping/lifting of the front derailleur to meet the new chainring.
If however, you have one or both BBs of the press-fit variety you will have a more complicated task ahead of you. Most permutations are possible using one of the many adaptors available but, by the time you have bought the removal/fitting tool, it's often cheaper to use your LBS.
And by the way, I've got one bike with 52/36 and one with 50/34 and, under normal riding conditions, I can't tell the difference. Just saying.
Best of luck.