Avgas
Avgas is much more expensive here in the UK.
It averages around £1.95 Litre (Aprox £7.40 US Gallon) whereas your paying about $1.63 Litre @ $6.20 US Gal. (£1.09 Litre @ £4.16 US Gal) Interesting you mention Self-Serve. I havent experienced anything else here?
How do you get on with Maintenance flying/owning a Twin? Are the schedules more or less the same? You must have to budget a huge amount of cash for the engine fund(s).
I think in general, aviation is much more affordable in the US. Landing fees here in the UK vary enormously. From the large(ish) International Airports - Exeter £27.40 <1Ton, Inverness £17.50, Cambridge £25, Bristol £35 to name a few. Smaller GA fields vary from £5 - £20 depending on facilities.