If you look on the technical forum and do a search on spark plugs, you will find endless info on what people think as being the best and how to do the job.

As for general servicing items such as filters, just try Halfords. They may not have the items on the shelf, but they can get them within a couple of days. I have had air and oil filters, timing belt and brake pads from them.

A good motor factors will get the plugs for you.

Happy servicing!!

Tony