A little late reply here, but right now, in Texas, I've got my nephew digging a 60in X 16in X 4ft hole just outside my home office. Into it I'll be placing a 40ft copper tubing "radiator". This with be the "core" of a geothermal loop to cool my mac. Yeah, it's wildly watercooled because the mods cause me to exceed the TDP (it's a MacPro1,1) of the case, but even before that my office got uncomfortably hot. Now it just causes my computer to shut down when I try to encode video. Not good.
In the UK you should be able to do the same (well, cool your room at least) with just a ground loop, a cheap pump, and a fan with more copper tubing coiled behind it. My project has ended up costing me quite a bit because of its complexity and mistakes make along the way, but a simple system to cool just the room should cost less than £150-200 and is definitely a DIY project you and your dad could do.
One of of the biggest reasons to do this are the electricity (cooling) costs saved for me, literally several hundred $ per year. And it's "Green" cooling. But the biggest reason is for the amount of science I've learned in the past 3 months.
Talk to your Dad about it. It's been fun, and would be a good project for a young Scottish engineer!