I did my PPL at Welshpool, so...
(a) It's hard to spot. It's not a former RAF field, and has only the 1 runway, no taxiway, so it has a small footprint. Add that to the fact that it's in a valley, and you are asking for trouble. Hence the bit in the AIP about not descending below MSA until sure. If possible tune in the WPL NDB (323, I think) and/or use GPS to confirm. (The NDB is no use at all at more than 5 miles, though, thanks to the hills).
(b) On approach to 22 with a westerly wind watch out for windshear created by the hangars on the right (West) of the runway.
(c) Circuits are high (1500ft QFE) for a reason - the hills can be scary particularly on downwind for 04, or at least I used to think so as a solo student...!
(d) Watch out for the 'devil's aerial' a bit east of the extended centreline of 22, southeast of the field. It's about 150ft high and hard to spot. It's not really high enough to be a problem but used to scare my instructor...
(e) Read the noise abatement procedures - I'm sure you will anyway - as there are a few nimbys, as usual.
Oh, and have fun! I had a great time there in 2001.
Tim