Halfords are convenient, and they often have 3 for 2s on, autoglym or meguiars stuff are pretty good, you need to try some as a lot if it is personal preference and works differently based on colour or paint thickness or finish.

I use valet pro fo snow foam and wheel cleaner, autoglym for bug and tar and interior stuff, and Meg's for tyres, polish and wax (3 stage)