If you want something you can pick up at Halfords, you cant go wrong with Autoglym. I would use their Super Resin Polish as it isn't very abrasive and so is a good balance between a proper polish and a pre-wax cleaner. I'd then follow that with either extra gloss protection or HD wax.
Beyond that, I really like the Dodo Juice range, https://www.cleanyourcar.co.uk/dodo-juice Lime Prime is described as a pre-wax cleaner but really is a similar polish to Autoglyms SRP, which is why they also make Lime Prime Lite, which really is a pre wax cleaner. They offer a range of colour specific hard and soft waxs, although all will work on any colour, they offer some benefits for their targeted colour. Personally I prefer working with the hard wax and so would recommend banana armour for your car.