Hi Thump,
First of all, £143 sounds like a lot of money, but it's probably roughly right for the south - especially the south-east. Does your club have any other, smaller aircraft that they'll rent for less?
As for whether you're getting the most out of an hour of flying, there are so many pros and cons of different airfields that it's difficult to give an answer. As you say, you're getting good RT practice where you are, and you won't get that without the odd delay or two. On the other hand, you're missing out on other things, such as being forced to rely on yourself to spot traffic in the circuit (it's always your responsibility, of course, but having the safety net of ATC taken away from you might be difficult when you first go to non-controlled fields.)
Personally, I did all my training from an un-controlled grass airfield. When I got my PPL, I'd landed at a total of 2 airfields with hard runways, and 1 airfield with ATC (although that was Bournemouth, so I was mixing it with a couple of the big guys...)
When I had 100 hours, I went to America, and logged a further 100 hours flying from a field with full ATC - ground frequency, and two tower frequencies. I made a point of flying Class B transitions whenever it was appropriate. And I flew into Tucson International several times - they have a complete set of busy ATC frequencies there, including ATIS, Delivery, Ground, and several Tower, Departure and Approach frequencies.
So I'd suggest that you stay where you are, as long as you're happy with the instruction you're getting - you'll get valuable experience there. And, when you get your license, you'll need to fly into different types of airfield in order to get experience there, too. Exactly the same way everyone else does.
Hope that makes sense! Just re-read it, and it was very waffly - sorry!
FFF
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