I usually carry a couple of spare inner tubes. I have broken a Presta but its a rare event.
Try and use the bike you have to start with. See the ultralight touring site for ideas.

In the UK market, you have trad touring bikes from Dawes, Ridgeback, Edinburgh Cycles, and lots of smaller names such as Hewitt. There is a lively market in used ones, which include the premium names such as Mercian, Bob Jackson.
A modern alternative is the cyclo-cross bike, esp disc-brake equipped and the Euro-style trekking bike with trekking/butterfly handlebars. Plenty of people tour on standard "hybrid" style models.

In Ireland you have a good network of hostels so I found I could tour without camping. You may want to invest in a lightweight solo tent, sleeping bag and some cooking gear.