In general, (because I'm not in the UK, nor the aircraft rental business) I think that you'll find that aircraft providers are not raking in tremendous profits in that business. Indeed, when you consider that a rental pilot turns up, signs out the aircraft and goes out flying, there is a lot that that pilot does not have to concern themselves with - which is still costing money. When you consider the unplanned costs of a mechanical away from home, and aircraft which gets weathered out, and cannot generate income until it is picked up, but still costs money, and a number of other surprise costs, you might think that you're getting a deal not having to make any investment, nor take any risk.
I know that when I took my helicopter training (Sw300) the school told me well off that they were not making money on the rental of the helicopter. They would honour the agreed hourly price, and they would keep the two helicopters until myself, and the one other student had completed their training, and the machines would be sold. That is what happened - and I lost the opportunity to fly them further (unless I wanted to buy one!).
When you consider the number of people (jobs) required to keep an aircraft flying, and the fact that each of those people expects to be fairly paid for their time, it's not surprising that flying is costly. Which of the many aviation service providers could you look in the eye, and say "I do not wish to pay you for the work I expect of you."?
I took a different route: I bought a plane 29 years ago, which I have paid to maintain, insure, repair and upgrade all these years. I bought 100 acres upon which to build my runway and hangar. Other than gas, insurance, and maintenance costs, I don't pay anyone for my flying, but I sure invested a lot to do it that way! I won't work out the costs, and I hope that I am still ahead of rental costs, but I'm not certain. In the mean time, I have to cut the grass, plow the snow, and pay the taxes on the property - what is my time worth!
It is what it is. If the school down the road offers a better deal, maybe it's worth the journey, but flying is voluntary in any case....