I have some Recaro Pro Kevlar seats I got for 100 quid on ebay, which everyone I know is saying is the bargain of the century. I love them, they're really good for holding you in, and they look great. I'd invite you to take a look, but you're in wales and im in the south east england aha! I put some TRS 5 point harnesses in, to enable me to take out all of the old seats and runners. I made up some subframes from aerospace aluminium, and put aluminium side mounts on to keep the weight to a bare minimum. My car isn't completely stripped or anything, I just wanted to put as little weight in as possible.
One thing regarding harnesses, is you want the ones with the forged aluminium adjusters, instead of the pressed steel ones, as they are a thousand times easier to adjust, every time you get in the car! I used to commute 5 hours a day in my buckets with harnesses, so anyone that tells you it ruins it as a daily just has a lack of commitment! I'd highly recommend a 5 or 6 point over a 4 point harness, I find it much more secure.
If you are fitting buckets, you'll really want harnesses to hold you in properly, under braking you don't want to be coming out of your seat and trying to hold yourself in place on the wheel and footrest. However you mount your seats, you want to be able to grab them and pull them in any direction as hard as you can with absolutely no movement.
Targas, 12 cars, autosolos are all happy with the standard safety equipment, but allow you to uprate it if you want. Beware marshalls will check the quality of fitment of buckets and harnesses if you have them.
Keep a look on ebay for excellent deals, I clicked the buy it now button on my seats within 4 minutes of them going online, and picked them up within 3 hours, and they were 100 miles away. Out of date seats and harnesses are much better value than the in date ones, since you'll be wasting the FIA date time if you buy them new.
I also fitted a Sabelt steering wheel, which is much better than the original, but requires either a PH1 stalk for the horn, or the drilling of a hole to mount a button.