I should certainly give it a whirl if you are content with your own company while travelling. Otherwise you'll have been very unlucky if you do not come away having met many new friends. If you want to guarantee to play certain top level courses you would be wise to book them in advance. You stand as much chance as anyone else in the ballot for TOC and if your name doesn't come out of the hat on one day there are lots of other first-rate courses in the area, so you won't miss out while waiting for the next day's ballot.
You would be wise to equip yourself with a golfing guide book or two which feature the lesser-known courses. It might just influence the route you take between, say, Perth and Inverness. I like David J Whyte's Globetrotter Golfer's Guide to Scotland (ISBN 1 85974 276 9) and Philip Reid's Globetrotter Golfer's Guide to Ireland (ISBN 1 85974 669 1), both published by New Holland. There is a series of Golfers Guides published by Travel Publishing Limited, and I have the guide to Ireland here, written by Dermot Gilleece (ISBN 1-902-00749-2). There's not a lot of description but most of the vital information is present and he does feature many lesser-known golf courses that might well appeal to you in non-tourist areas - Heath in Co Laois, Enniskillen in Co Fermanagh, for instance. Sadly, the Times Guide with which I used to be associated will not be republished. THE AA Guide and Sunday Telegraph Guides are both still in publication and offer enough information to find off-the-beaten-track clubs and courses.
If you are taking a digital camera with you mark down each and every photo you take on the scorecard. You'll never remember which hole was which afterwards.
The advice to take a caddie may be sound, but you'll only get them at the big, famous clubs. Very often, if you ring the professional a few days in advance, a caddie can be provided at a lesser course, but it will almost certainly be a junior member who wants a bit of extra pocket money in the summer holidays. It is unlikely he or she will be any use in reading putts, advising on yardages etc. And I have to say that there are quite a few lesser courses where it is not immediately apparent what the correct line is from the tee - Ardglass in County Down is an example. It is great fun and very scenic, but definitely a course to play with a local, for the first time, anyway.