I also live in South Wales, near Swansea. Regularly out in the hills within a mile or two in most directions. There is no getting away from it without only doing one or two short flat routes along the coastal paths.
I run a compact with 11-28 and am now finding that I rarely need the 28. Now and again I will use it, but that's just because it's there.
A couple of mates have semi-compacts with the same 11-28. With them on the 28, it equates to me using the 25. On last weeks ride, we hit some short hills with 14% average, 22% max, over sections of 0.3 - 0.4 miles. I deliberately only limited myself to the 25 max. Was surprised to see that it didn't feel that much harder. Was even down to 23 on some during my little experiment.
I guess the result shows that we can avoid the higher gears if we try, even on the steep stuff.
As far avoiding hills until ready for it. I started out 20 months ago by doing those coastal paths regularly. I certainly got faster, but it did f help me to do the hills any better than when I started. The Only way to get better on the hills is to do those hills regularly!