I bought a couple of tyre levers on eBay, also valves, valve puller, and tyre lubricant, all for about £20. The difficult bit is getting the old tyre off the rim but there are various ways of doing this and it can actually turn out quite easy - I made a T-piece of 2 bits of wood - one long, about 1.5m (the lever) and one short, 40cm or so, (the fulcrum?) then with wheel flat on ground, short piece on wheel rim edge, long end under towbar on my Land Rover, press down on other end and off the rim goes the old tyre. Then easily removed using tyre levers, with a little assistance from a hammer - basically replicating what your professional tyre fitters do.
Putting the new tyres on is easy as long as you remember to make use of the trough in the middle of the wheel to allow the tyres to go over the rim. Plus you need the tyre lubricant - slightly diluted washing up liquid can also work.
Then comes the hard bit - blowing the tyre up and getting it to pop on to the rim - pretty much impossible with just a foot pump but easy if you have a compressor with a reservoir. Otherwise you could always pop down to Tesco's and put 20p in their airline and select 'flat tyre' (but I used a compressor so can't guarantee the Tesco method).