I'm not conversant with all the UK rules, but the general rules about aircraft operation are pretty universal. A few include:
Flying 150 knots will likely cost you half again to twice the cost to fly 100 knots. That's fine, as long as you're willing to pay. But that cost is attached to the plane, whenever it flies, not just when it goes fast!
Non certified aircraft require maintenance just as certified ones do. True, there are fewer regulatory costs, but be careful selecting non certified to save maintenance costs, you still must maintain the plane to be airworthy, and pay that cost. You don't do less maintenance because its non certified!
The fact that you own, does not prevent you still renting. I've owned my C 150 for 28 years. It would never carry my wife and four kids (though it did carry my wife and two of them, when they were little). I have, on occasion rented or borrowed to carry more of them together, or go faster on a long trip.
30 hours a year won't really pay back the investment in the plane, so you're subsidizing it, which is fine, or you'd better plan to have it return an investment, if you own it.
Slow planes still get there. My 150 is the faster of my two planes. I took my wife, two folding bikes, and a bit of luggage 1500 miles to the Bahamas for a week. It was still faster than driving!